OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
J. Choi, N. Pippenger, Counting the Angels and Devils in Escher's Circle Limit IV, arXiv preprint arXiv:1310.1357 [math.CO], 2013.
Index entries for linear recurrences with constant coefficients, signature (2,2, 2,-1).
MATHEMATICA
CoefficientList[Series[(1+4x+10x^2+4x^3+x^4)/(1-2x-2x^2-2x^3+x^4), {x, 0, 30}], x] (* Harvey P. Dale, Apr 12 2017 *)
Join[{1}, LinearRecurrence[{2, 2, 2, -1}, {6, 24, 66, 192}, 50]] (* Vincenzo Librandi, Apr 14 2017 *)
PROG
(Magma) I:=[1, 6, 24, 66, 192]; [n le 5 select I[n] else 2*Self(n-1)+2*Self(n-2)+2*Self(n-3)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Apr 14 2017
(PARI) x='x + O('x^30); Vec((1 + 4*x + 10*x^2 + 4*x^3 + x^4)/(1 - 2*x - 2*x^2 - 2*x^3 + x^4)) \\ Indranil Ghosh, Apr 14 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Dec 24 2013
STATUS
approved