OFFSET
0,2
FORMULA
a(0) = 1; a(n) = a(n-1) + Sum_{k=0..n-1} a(floor(k/3)) * a(n-1-k).
PROG
(PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=v[i]+sum(j=0, i-1, v[j\3+1]*v[i-j])); v;
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 26 2023
STATUS
approved