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A124403
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Sum[ i^j, {i,1,n}, {j,1,n} ] - 1.
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0
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0, 7, 55, 493, 5698, 82199, 1419759, 28501115, 651233660, 16676686695, 472883843991, 14705395791305, 497538872883726, 18193397941038735, 714950006521386975, 30046260016074301943, 1344648068888240941016
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| p divides a(p-2) for prime p>2. p^k divides a(p^k-2) for prime p>2.
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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.
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MATHEMATICA
| Table[Sum[i^j, {i, 1, n}, {j, 1, n}]-1, {n, 1, 25}]
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CROSSREFS
| Cf. A086787 = Sum(Sum(i^j, j=1..n), i=1..n).
Sequence in context: A116862 A096307 A199564 * A005012 A123784 A091695
Adjacent sequences: A124400 A124401 A124402 * A124404 A124405 A124406
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KEYWORD
| nonn
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Dec 14 2006
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