OFFSET
0,2
FORMULA
a(n) = 1 + Sum_{k=1..n} Sum_{j=0..n-k} binomial(k, j)*a(j).
PROG
(PARI) {a(n)=1+sum(k=1, n, sum(j=0, n-k, binomial(k, j)*a(j)))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Nov 23 2004
STATUS
approved