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A124403 Sum[ i^j, {i,1,n}, {j,1,n} ] - 1. 0
0, 7, 55, 493, 5698, 82199, 1419759, 28501115, 651233660, 16676686695, 472883843991, 14705395791305, 497538872883726, 18193397941038735, 714950006521386975, 30046260016074301943, 1344648068888240941016 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

p divides a(p-2) for prime p>2. p^k divides a(p^k-2) for prime p>2.

LINKS

Table of n, a(n) for n=1..17.

FORMULA

a(n) = Sum[ i^j, {i,1,n}, {j,1,n} ] - 1. a(n) = Sum[ i*(i^n-1)/(i-1), {i,2,n} ] + n - 1. a(n) = A086787(n) - 1.

MATHEMATICA

Table[Sum[i^j, {i, 1, n}, {j, 1, n}]-1, {n, 1, 25}]

CROSSREFS

Cf. A086787 = Sum(Sum(i^j, j=1..n), i=1..n).

Sequence in context: A096307 A199564 A225032 * A005012 A123784 A091695

Adjacent sequences:  A124400 A124401 A124402 * A124404 A124405 A124406

KEYWORD

nonn

AUTHOR

Alexander Adamchuk, Dec 14 2006

STATUS

approved

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Last modified July 22 14:39 EDT 2019. Contains 325222 sequences. (Running on oeis4.)