OFFSET
0,2
FORMULA
a(n) = (n+1)^3*A107673(n). [Corrected by Petros Hadjicostas, Mar 11 2021]
a(n) = Sum_{r=1..(n+1)} (-1)^(r-1) * Sum_{s_1, ..., s_r} (s_1^(-1)/(Product_{j=1..r} s_j!)) * Product_{j=1..r} (Sum_{i=1..j} s_i)^(3*s_j)), where the second sum is over lists (s_1, ..., s_r) of positive integers s_i such that Sum_{i=1..r} s_i = n + 1. (Thus, the second sum is over all compositions of n + 1.) - Petros Hadjicostas, Mar 11 2021
PROG
(PARI) {a(n)=local(P=matrix(n+1, n+1, r, c, if(r>=c, (r^3)^(r-c)/(r-c)!)), D=matrix(n+1, n+1, r, c, if(r==c, r))); (P^-1*D*P)[n+1, 1]}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jun 07 2005
STATUS
approved