OFFSET
1,3
FORMULA
a(n) = n!*T(n,1), T(n,m) = sum(k=1..n-m, T(n-m,k)*m^k/k! - 2^(k+m-n-1)*binomial(k+m-1,n-k-m+1)*T(k+m-1,m)), n>m, with T(n,n)=1.
PROG
(Maxima)
array(BB, 100, 100);
fillarray (BB, makelist (-1, i, 1, 1000));
T(n, m):=if BB[n, m]=-1 then BB[n, m]:(if n=m then 1 else sum(T(n-m, k)*m^k/k!-2^(k+m-n-1)*binomial(k+m-1, n-k-m+1)*T(k+m-1, m), k, 1, n-m)) else BB[n, m];
makelist(n!*T(n, 1), n, 1, 27);
CROSSREFS
KEYWORD
sign
AUTHOR
Vladimir Kruchinin, Dec 05 2011
STATUS
approved