OFFSET
0,7
FORMULA
a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/4)} (-1)^k * binomial(n-1-3*k,k) * a(n-1-3*k).
PROG
(PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=sum(j=0, (i-1)\4, (-1)^j*binomial(i-1-3*j, j)*v[i-3*j])); v;
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Feb 25 2023
STATUS
approved