OFFSET
0,6
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (2,2,-6,0,6,-2,-2,1).
FORMULA
a(n) = +2 a(n-1) +2 a(n-2) -6 a(n-3) +6 a(n-5) -2 a(n-6) -2 a(n-7) +a(n-8). - R. J. Mathar, Mar 11 2012
G.f.: x^4*(1 + 3*x + 3*x^2) / ((1 - x)^5*(1 + x)^3). - Colin Barker, Jul 28 2013
From Colin Barker, May 04 2017: (Start)
a(n) = n^2 * (7*n^2 - 36*n + 44) / 192 for n even.
a(n) = (7*n^4 - 36*n^3 + 38*n^2 + 36*n - 45) / 192 for n odd.
(End)
PROG
(PARI) concat(vector(4), Vec(x^4*(1 + 3*x + 3*x^2) / ((1 - x)^5*(1 + x)^3) + O(x^60))) \\ Colin Barker, May 04 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Nov 10 2005
STATUS
approved