OFFSET
1,2
FORMULA
a(n)=T(n,1), T(n,m)=1/2*(binomial(n-1,m-1)*2^(n-m)-(sum(k=m+1..n-1, T(k,m)*sum(i=k..n, T(n,i)*binomial(k,i-k)*(-2)^(i-k)))+sum(i=m+1,n, T(n,i)*binomial(m,i-m)*(-2)^(i-m)))), T(n,n)=1.
PROG
(Maxima)
T(n, m):=if n=m then 1 else 1/2*(binomial(n-1, m-1)*2^(n-m)-(sum(T(k, m)*sum(T(n, i)*binomial(k, i-k)*(-2)^(i-k), i, k, n), k, m+1, n-1)+sum(T(n, i)*binomial(m, i-m)*(-2)^(i-m), i, m+1, n)));
makelist(T(n, 1), n, 1, 7);
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Kruchinin, Mar 11 2012
STATUS
approved