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Search: id:A097438
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| A097438 |
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a(0) = 0, a(1) = 1, for n >= 2, a(n) = sum{k|n} a(k) a(n-k). |
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+0
1
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| 0, 1, 1, 1, 2, 2, 5, 5, 14, 19, 37, 37, 146, 146, 317, 537, 1342, 1342, 4312, 4312, 13751, 19648, 34768, 34768, 178350, 205852, 405518, 665796, 1626743, 1626743, 6019892, 6019892, 19591134, 26897442, 48289540, 68463039, 270214317, 270214317
(list; graph; listen)
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OFFSET
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0,5
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COMMENT
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If k in the sum in the definition is taken only over the proper divisors of n, the sequence is the same.
a(p)=a(p-1) if p is a prime. - Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 23 2004
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EXAMPLE
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a(8) = a(1)*a(7) + a(2)*a(6) + a(4)*a(4) + a(8)*a(0) = 5 + 5 + 4 + 0 = 14
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MATHEMATICA
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a[0] = 0; a[1] = 1; a[n_] := a[n] = Block[{d = Drop[ Divisors[n], -1]}, Plus @@ Flatten[(a /@ d)*(a /@ (n - d))]]; Table[ a[n], {n, 0, 38}] (from Robert G. Wilson v Aug 23 2004)
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CROSSREFS
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Adjacent sequences: A097435 A097436 A097437 this_sequence A097439 A097440 A097441
Sequence in context: A099363 A106181 A098887 this_sequence A055879 A056470 A056471
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Aug 22 2004
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 23 2004
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