OFFSET
0,3
FORMULA
Binomial transform equals A125273.
a(n)=sum(k=1..n, sum(i=k..n, binomial(i-1,k-1)*binomial(i,n-i))*a(k-1)), n>0,a(0)=1. [Vladimir Kruchinin, May 02 2012]
PROG
(PARI) {a(n)=local(G=1+x+x*O(x^n)); for(i=0, n, G=1+x*subst(G, x, x/(1-x)^2)/(1-x)); polcoeff(subst((G-1)/x, x, x/(1+x))/(1+x), n)}
(Maxima) a(n):=if n=0 then 1 else sum(sum(binomial(i-1, k-1)*binomial(i, n-i), i, k, n)*a(k-1), k, 1, n); [Vladimir Kruchinin, May 02 2012]
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Paul D. Hanna, Aug 21 2007
STATUS
approved