OFFSET
0,3
FORMULA
a(n) = [x^n] x * (1+4*x+x^2)/((1-n*x) * (1-x)^4).
a(n) = n * (n^n * (n^2 + 4*n + 1) - n^5 - 3*n^2 - n - 1)/(n-1)^4 for n > 1.
PROG
(PARI) a(n) = sum(k=1, n, k^3*n^(n-k));
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Dec 28 2023
STATUS
approved