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Search: a134501 -id:a134501
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a(n) = Fibonacci(6n+4).
+10
12
3, 55, 987, 17711, 317811, 5702887, 102334155, 1836311903, 32951280099, 591286729879, 10610209857723, 190392490709135, 3416454622906707, 61305790721611591, 1100087778366101931, 19740274219868223167, 354224848179261915075, 6356306993006846248183
OFFSET
0,1
COMMENTS
Gives those numbers which are Fibonacci numbers in A103135.
Generally, for any sequence where a(0)= Fibonacci(p), a(1) = F(p+q) and Lucas(q)*a(1) +- a(0) = F(p+2q), then a(n) = L(q)*a(n-1) +- a(n-2) generates the following Fibonacci sequence: a(n) = F(q(n)+p). So for this sequence, a(n) = 18*a(n-1) - a(n-2) = F(6n+4): q=6, because 18 is the 6th Lucas number (L(0) = 2, L(1)=1); F(4)=3, F(10)=55 and F(16)=987 (F(0)=0 and F(1)=1). See Lucas sequence A000032. This is a special case where a(0) and a(1) are increasing Fibonacci numbers and Lucas(m)*a(1) +- a(0) is another Fibonacci. - Bob Selcoe, Jul 08 2013
a(n) = x + y where x and y are solutions to x^2 = 5*y^2 - 1. (See related sequences with formula below.) - Richard R. Forberg, Sep 05 2013
FORMULA
G.f.: (x+3)/(x^2-18*x+1).
a(n) = 18*a(n-1) - a(n-2) for n>1; a(0)=3, a(1)=55. - Philippe Deléham, Nov 17 2008
a(n) = A007805(n) + A075796(n), as follows from comment above. - Richard R. Forberg, Sep 05 2013
a(n) = ((15-7*sqrt(5)+(9+4*sqrt(5))^(2*n)*(15+7*sqrt(5))))/(10*(9+4*sqrt(5))^n). - Colin Barker, Jan 24 2016
a(n) = S(3*n+1, 3) = 3*S(n,18) + S(n-1,18), with the Chebyshev S polynomials (A049310), S(-1, x) = 0, and S(n, 18) = A049660(n+1). - Wolfdieter Lang, May 08 2023
MATHEMATICA
Table[Fibonacci[6n+4], {n, 0, 30}]
LinearRecurrence[{18, -1}, {3, 55}, 20] (* Harvey P. Dale, Mar 29 2023 *)
Table[ChebyshevU[3*n+1, 3/2], {n, 0, 20}] (* Vaclav Kotesovec, May 27 2023 *)
PROG
(Magma) [Fibonacci(6*n +4): n in [0..100]]; // Vincenzo Librandi, Apr 17 2011
(PARI) a(n)=fibonacci(6*n+4) \\ Charles R Greathouse IV, Feb 05 2013
KEYWORD
nonn,easy
AUTHOR
Creighton Dement, Jan 24 2005
EXTENSIONS
Edited by N. J. A. Sloane, Aug 10 2010
STATUS
approved
a(n) = Fibonacci(7n).
+10
10
0, 13, 377, 10946, 317811, 9227465, 267914296, 7778742049, 225851433717, 6557470319842, 190392490709135, 5527939700884757, 160500643816367088, 4660046610375530309, 135301852344706746049, 3928413764606871165730
OFFSET
0,2
FORMULA
G.f.: -13*x / ( -1+29*x+x^2 ). a(n) = 13*A049667(n). - R. J. Mathar, Apr 17 2011
a(n) = A000045(A008589(n)). - Michel Marcus, Nov 08 2013
MATHEMATICA
Table[Fibonacci[7n], {n, 0, 30}]
{a, b}={0, 13}; Do[Print[c={a, b}.{1, 29}]; a=b; b=c, {30}] (* Zak Seidov, Nov 02 2009 *)
PROG
(MuPAD) numlib::fibonacci(7*n) $ n = 0..25; // Zerinvary Lajos, May 09 2008
(Sage) [fibonacci(7*n) for n in range(0, 16)] # Zerinvary Lajos, May 15 2009
(Magma) [Fibonacci(7*n): n in [0..100]]; // Vincenzo Librandi, Apr 17 2011
(PARI) a(n)=fibonacci(7*n) \\ Charles R Greathouse IV, Jun 11 2015
KEYWORD
nonn,easy
AUTHOR
Artur Jasinski, Oct 28 2007
EXTENSIONS
Offset changed from 1 to 0 by Vincenzo Librandi, Apr 17 2011
STATUS
approved
a(n) = Fibonacci(7n + 6).
+10
10
8, 233, 6765, 196418, 5702887, 165580141, 4807526976, 139583862445, 4052739537881, 117669030460994, 3416454622906707, 99194853094755497, 2880067194370816120, 83621143489848422977, 2427893228399975082453
OFFSET
0,1
FORMULA
G.f.: (-8-x) / (-1 + 29*x + x^2). - R. J. Mathar, Jul 04 2011
a(n) = A000045(A017053(n)). - Michel Marcus, Nov 08 2013
a(n) = 29*a(n-1) + a(n-2). - Wesley Ivan Hurt, Mar 15 2023
MATHEMATICA
Table[Fibonacci[7n+6], {n, 0, 30}]
LinearRecurrence[{29, 1}, {8, 233}, 20] (* Harvey P. Dale, Jul 21 2021 *)
PROG
(Magma) [Fibonacci(7*n +6): n in [0..100]]; // Vincenzo Librandi, Apr 17 2011
(PARI) a(n)=fibonacci(7*n+6) \\ Charles R Greathouse IV, Jun 11 2015
KEYWORD
nonn,easy
AUTHOR
Artur Jasinski, Oct 28 2007
EXTENSIONS
Offset changed from 1 to 0 by Vincenzo Librandi, Apr 17 2011
STATUS
approved
a(n) = Fibonacci(7n + 2).
+10
6
1, 34, 987, 28657, 832040, 24157817, 701408733, 20365011074, 591286729879, 17167680177565, 498454011879264, 14472334024676221, 420196140727489673, 12200160415121876738, 354224848179261915075, 10284720757613717413913
OFFSET
0,2
FORMULA
G.f.: (-1-5*x) / (-1 + 29*x + x^2). - R. J. Mathar, Apr 17 2011
a(n) = A000045(A017005(n)). - Michel Marcus, Nov 07 2013
MATHEMATICA
Table[Fibonacci[7n+2], {n, 0, 30}]
PROG
(Magma) [Fibonacci(7*n +2): n in [0..100]]; // Vincenzo Librandi, Apr 17 2011
(PARI) a(n)=fibonacci(7*n+2) \\ Charles R Greathouse IV, Jun 11 2015
KEYWORD
nonn,easy
AUTHOR
Artur Jasinski, Oct 28 2007
EXTENSIONS
Offset changed from 1 to 0 by Vincenzo Librandi, Apr 17 2011
STATUS
approved
a(n) = Fibonacci(7*n+1).
+10
5
1, 21, 610, 17711, 514229, 14930352, 433494437, 12586269025, 365435296162, 10610209857723, 308061521170129, 8944394323791464, 259695496911122585, 7540113804746346429, 218922995834555169026, 6356306993006846248183
OFFSET
0,2
FORMULA
G.f.: ( -1+8*x ) / ( -1+29*x+x^2 ). - R. J. Mathar, Apr 17 2011
2*a(n) = Fibonacci(7*n) + Lucas(7*n). - Bruno Berselli, Oct 13 2017
MATHEMATICA
Table[Fibonacci[7 n + 1], {n, 0, 30}]
PROG
(Magma) [Fibonacci(7*n+1): n in [0..100]]; // Vincenzo Librandi, Apr 16 2011
(PARI) a(n)=fibonacci(7*n+1) \\ Charles R Greathouse IV, Jun 11 2015
KEYWORD
nonn,easy
AUTHOR
Artur Jasinski, Oct 28 2007
EXTENSIONS
Offset corrected by Vincenzo Librandi, Apr 16 2011
STATUS
approved
a(n) = Fibonacci(7n + 5).
+10
5
5, 144, 4181, 121393, 3524578, 102334155, 2971215073, 86267571272, 2504730781961, 72723460248141, 2111485077978050, 61305790721611591, 1779979416004714189, 51680708854858323072, 1500520536206896083277
OFFSET
0,1
FORMULA
From R. J. Mathar, Apr 17 2011: (Start)
G.f.: (-5+x) / (-1 + 29*x + x^2).
a(n) = 5*A049667(n+1) - A049667(n). (End)
MATHEMATICA
Table[Fibonacci[7n+5], {n, 0, 30}]
LinearRecurrence[{29, 1}, {5, 144}, 20] (* Harvey P. Dale, Apr 24 2017 *)
PROG
(Magma) [Fibonacci(7*n+5): n in [0..100]]; // Vincenzo Librandi, Apr 17 2011
(PARI) a(n)=fibonacci(7*n+5) \\ Charles R Greathouse IV, Jun 11 2015
KEYWORD
nonn,easy
AUTHOR
Artur Jasinski, Oct 28 2007
EXTENSIONS
Offset changed from 1 to 0 by Vincenzo Librandi, Apr 17 2011
STATUS
approved

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