OFFSET
0,2
PROG
(PARI) {a(n)=local(M=matrix(n+1, n+1)); for(m=0, n, for(k=0, m, M[m+1, k+1]=if(m==0||k==0, 1, M[m+1, k]+(k+1)*M[m, k+1]))); return(sum(i=0, n, M[n+1, i+1]))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jan 04 2005
EXTENSIONS
More terms from Robert C. Lyons, Jul 19 2024
STATUS
approved