A062808 - OEIS

%I #15 Mar 26 2019 11:50:18

%S 0,2,15,108,970,11190,160125,2739128,54480996,1234567890,31384283755,

%T 884241366756,27342891567342,920521275489998,33512287529147385,

%U 1311768467463790320,54933923640889550728,2450641333409472928554

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

%C Permutational numbers A134640 isomorphic with permutation matrix generators of cyclic groups, n-th root of unity matrices. - _Artur Jasinski_, Nov 07 2007

%H Seiichi Manyama, <a href="/A062808/b062808.txt">Table of n, a(n) for n = 1..387</a>

%F a(n) = (n^(n+1)-n^3+n^2-n)/(n-1)^2 for n>1. - _Dean Hickerson_, Jun 26, 2001

%t Sum[n^i*(n - i), {i, 1, n}]

%t 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 *)

%o (PARI) a(n) = sum(i=1, n, n^i*(n-i)); \\ _Michel Marcus_, Mar 26 2019

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

%K nonn,easy

%O 1,2

%A _Olivier Gérard_, Jun 23 2001