A062808 a(n) = Sum_{i=1..n} n^i * (n - i).

0, 2, 15, 108, 970, 11190, 160125, 2739128, 54480996, 1234567890, 31384283755, 884241366756, 27342891567342, 920521275489998, 33512287529147385, 1311768467463790320, 54933923640889550728, 2450641333409472928554

Offset: 1

Author

Olivier Gérard, Jun 23 2001

Keywords

• nonn
• easy

Comments

Permutational numbers A134640 isomorphic with permutation matrix generators of cyclic groups, n-th root of unity matrices. - Artur Jasinski, Nov 07 2007

Links

• Seiichi Manyama, Table of n, a(n) for n = 1..387

Crossrefs

Cf. A134640, A134641, A134642, A134643, A134644, A023811.

Programs

Mathematica

Sum[n^i*(n - i), {i, 1, n}]
a = {}; b = {}; c = {}; Do[AppendTo[b, n]; c = b; AppendTo[c, 0]; AppendTo[a, FromDigits[c, n + 1]], {n, 1, 20}]; a (* Artur Jasinski, Nov 07 2007 *)

PARI

a(n) = sum(i=1, n, n^i*(n-i)); \\ Michel Marcus, Mar 26 2019

Formula

a(n) = (n^(n+1)-n^3+n^2-n)/(n-1)^2 for n>1. - Dean Hickerson, Jun 26 2001