OFFSET
0,2
COMMENTS
Interpolated zeros suppressed.
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0,15).
FORMULA
a(n) = b(2*n) where b(0)=1, b(1)=0, b(n) = (3 + 2*(n/2 mod 2))*b(n-2).
a(n) = A100747(2(n+1))/3.
a(2n) = 15^n, a(2n+1) = 5*15^n. - Ralf Stephan, May 16 2007
O.g.f.: (1+5*x)/(1-15*x^2). - Philippe Deléham, Dec 02 2011
MAPLE
a:=n->mul(4-(-1)^j, j=1..n):seq(a(n), n=0..23); # Zerinvary Lajos, Dec 13 2008
MATHEMATICA
CoefficientList[Series[(1+5x)/(1-15x^2), {x, 0, 30}], x] (* or *) LinearRecurrence[ {0, 15}, {1, 5}, 30] (* Harvey P. Dale, Oct 14 2013 *)
RecurrenceTable[{a[n] == (3 + 2*Mod[n/2, 2])*a[n - 2], a[0] == 1, a[1] == 0}, a, {n, 0, 50}][[1 ;; ;; 2]] (* G. C. Greubel, Apr 16 2018 *)
PROG
(PARI) x='x+O('x^30); Vec((1+5*x)/(1-15*x^2)) \\ G. C. Greubel, Apr 16 2018
(Magma) I:=[1, 5]; [n le 2 select I[n] else 15*Self(n-2): n in [1..30]]; // G. C. Greubel, Apr 16 2018
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Dec 06 2004
STATUS
approved