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Search: id:A019565
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| A019565 |
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If n = Sum 2^e_i, e_i distinct, then a(n) = Product prime_{e_{i+1}}. |
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18
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| 1, 2, 3, 6, 5, 10, 15, 30, 7, 14, 21, 42, 35, 70, 105, 210, 11, 22, 33, 66, 55, 110, 165, 330, 77, 154, 231, 462, 385, 770, 1155, 2310, 13, 26, 39, 78, 65, 130, 195, 390, 91, 182, 273, 546, 455, 910, 1365, 2730, 143, 286, 429, 858, 715, 1430, 2145, 4290
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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G.f. prod(k>=0, 1 + prime(k+1)*x^2^k), where prime(k)=A000040(k). - Ralf Stephan (ralf(AT)ark.in-berlin.de), Jun 20 2003
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MATHEMATICA
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Do[m=1; o=1; k1=k; While[ k1>0, k2=Mod[k1, 2]; If[k2\[Equal]1, m=m*Prime[o]]; k1=(k1-k2)/ 2; o=o+1]; Print[m], {k, 0, 55}] (Lei Zhou (lzhou5(AT)emory.edu), Feb 15 2005)
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CROSSREFS
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Sequence in context: A055944 A073740 A077320 this_sequence A133477 A039653 A106379
Adjacent sequences: A019562 A019563 A019564 this_sequence A019566 A019567 A019568
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KEYWORD
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nonn
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AUTHOR
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Marc LeBrun (mlb(AT)well.com)
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