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Search: id:A057623
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| A057623 |
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n! *(sum of reciprocals of all parts in unrestricted partitions of n). |
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+0
2
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| 1, 5, 29, 218, 1814, 18144, 196356, 2427312, 32304240, 475637760, 7460546400, 127525829760, 2302819079040, 44659367020800, 911770840108800, 19784985947596800, 449672462639769600, 10790180876185804800
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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FORMULA
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n! *sum_{k=1 to n} [sigma(k) p(n-k) /k], where sigma(n) = sum of positive divisors of n and p(n) = number of unrestricted partitions of n.
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EXAMPLE
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The unrestricted partitions of 3 are 1 + 1 + 1, 1 + 2 and 3. So a(3) = 3! *(1 + 1 + 1 + 1 + 1/2 + 1/3) = 29.
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CROSSREFS
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Sequence in context: A121143 A027048 A094856 this_sequence A087662 A113012 A000354
Adjacent sequences: A057620 A057621 A057622 this_sequence A057624 A057625 A057626
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Oct 09 2000
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