OFFSET
0,3
FORMULA
a(n) = (-1)^n + Sum_{k=0..n-1} a(floor(k/3)) * a(n-1-k).
PROG
(PARI) a_vector(n) = my(v=vector(n+1)); for(i=0, n, v[i+1]=(-1)^i+sum(j=0, i-1, v[j\3+1]*v[i-j])); v;
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 28 2023
STATUS
approved