OFFSET
0,3
PROG
(PARI) {a(n)=local(A2=vector(n+1, m, sum(k=0, m-1, 3^((m-k-1)*(m+k-2)/2)))); Vec(Ser(A2)^(1/2))[n+1]}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Mar 14 2006
STATUS
approved