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A062808 a(n) = Sum_{i=1..n} n^i * (n - i). 3
0, 2, 15, 108, 970, 11190, 160125, 2739128, 54480996, 1234567890, 31384283755, 884241366756, 27342891567342, 920521275489998, 33512287529147385, 1311768467463790320, 54933923640889550728, 2450641333409472928554 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Permutational numbers A134640 isomorphic with permutation matrix generators of cyclic groups, n-th root of unity matrices. - Artur Jasinski, Nov 07 2007
LINKS
FORMULA
a(n) = (n^(n+1)-n^3+n^2-n)/(n-1)^2 for n>1. - Dean Hickerson, Jun 26, 2001
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 *)
PROG
(PARI) a(n) = sum(i=1, n, n^i*(n-i)); \\ Michel Marcus, Mar 26 2019
CROSSREFS
Sequence in context: A037740 A037635 A154635 * A162773 A140637 A342963
KEYWORD
nonn,easy
AUTHOR
Olivier Gérard, Jun 23 2001
STATUS
approved

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Last modified March 28 05:39 EDT 2024. Contains 371235 sequences. (Running on oeis4.)