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A124403 a(n) = -1 + Sum_{i=1..n} Sum_{j=1..n} i^j. 1
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

G. C. Greubel, Table of n, a(n) for n = 1..385

FORMULA

a(n) = -1 + Sum_{i=1..n} Sum_{j=1..n} i^j.

a(n) = n - 1 + Sum_{j=2..n} j*(j^n - 1)/(j-1).

a(n) = A086787(n) - 1.

MAPLE

seq( n-1+add(j*(j^n-1)/(j-1), j=2..n), n=1..30); # G. C. Greubel, Dec 25 2019

MATHEMATICA

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

PROG

(PARI) vector(30, n, n-1 + sum(j=2, n, j*(j^n-1)/(j-1)) ) \\ G. C. Greubel, Dec 25 2019

(MAGMA) [0] cat [n-1 + (&+[j*(j^n-1)/(j-1): j in [2..n]]): n in [2..30]]; // G. C. Greubel, Dec 25 2019

(Sage) [n-1 + sum(j*(j^n-1)/(j-1) for j in (2..n)) for n in (1..30)] # G. C. Greubel, Dec 25 2019

(GAP) List([1..30], n-> n-1 + Sum([2..n], j-> j*(j^n-1)/(j-1)) ); # G. C. Greubel, Dec 25 2019

CROSSREFS

Cf. A086787.

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 August 10 08:44 EDT 2020. Contains 336369 sequences. (Running on oeis4.)