OFFSET
0,3
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 20810, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1).
FORMULA
G.f.: -(x^18 -x^17 +5*x^16 -6*x^15 +11*x^14 -28*x^13 +39*x^12 -67*x^11 +307*x^10 -374*x^9 -307*x^8 -67*x^7 -39*x^6 -28*x^5 -11*x^4 -6*x^3 -5*x^2 -x -1) / (x^20 -20810*x^10 +1). - Colin Barker, Dec 15 2013
a(n) = 20810*a(n-10) - a(n-20). - Vincenzo Librandi, Dec 15 2013
MATHEMATICA
Denominator[Convergents[Sqrt[774], 30]] (* Vincenzo Librandi, Dec 15 2013 *)
LinearRecurrence[{0, 0, 0, 0, 0, 0, 0, 0, 0, 20810, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1}, {1, 1, 5, 6, 11, 28, 39, 67, 307, 374, 20503, 20877, 104011, 124888, 228899, 582686, 811585, 1394271, 6388669, 7782940, 426667429}, 40] (* Harvey P. Dale, Jun 29 2015 *)
PROG
(Magma) I:=[1, 1, 5, 6, 11, 28, 39, 67, 307, 374, 20503, 20877, 104011, 124888, 228899, 582686, 811585, 1394271, 6388669, 7782940]; [n le 20 select I[n] else 20810*Self(n-10)-Self(n-20): n in [1..40]]; // Vincenzo Librandi, Dec 15 2013
CROSSREFS
KEYWORD
nonn,frac,easy
AUTHOR
EXTENSIONS
More terms from Colin Barker, Dec 15 2013
STATUS
approved