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Search: id:A159666
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| A159666 |
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a(0)=1. For n >= 1, a(n) = sum{k=1 to n} binomial(n,k) * GCD(n,k) * a(k-1). |
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+0
2
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| 1, 1, 4, 18, 104, 665, 5430, 45647, 457008, 4903380, 58782190, 735362309, 10577094600, 153445432699, 2462688382448, 41517435884340, 752130797186176, 13961847566945787, 284698729314200574, 5855054339061479491
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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a(n) is divisible by n, for all n >= 1.
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MATHEMATICA
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f[n_] := f[n] = Sum[Binomial[n, k] GCD[n, k] f[k - 1], {k, n}]; f[0] = 1; Table[f@n, {n, 0, 20}] [From Robert G. Wilson v (rgwv(AT)rgwv.com), May 27 2009]
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CROSSREFS
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A159667
Sequence in context: A135177 A137958 A064852 this_sequence A051827 A007711 A020114
Adjacent sequences: A159663 A159664 A159665 this_sequence A159667 A159668 A159669
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Apr 19 2009
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), May 27 2009
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