OFFSET
0,3
LINKS
Index entries for linear recurrences with constant coefficients, signature (-1,-3,-3,-1).
FORMULA
a(n) = -a(n-1) - 3*a(n-2) - 3*a(n-3) - a(n-4).
G.f.: 1/(1 + x*(1+x)^3).
PROG
(PARI) a(n) = sum(k=0, n, (-1)^k*binomial(3*k, n-k));
(PARI) my(N=40, x='x+O('x^N)); Vec(1/(1+x*(1+x)^3))
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Seiichi Manyama, Jan 25 2023
STATUS
approved