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Search: id:A023881
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| A023881 |
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Number of partitions in expanding space: sigma(n,q) is the sum of the q-th powers of the divisors of n. |
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+0
1
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| 1, 1, 3, 12, 82, 725, 8811, 128340, 2257687, 45658174, 1052672116, 27108596725, 772945749970, 24137251258926, 819742344728692, 30069017799172228, 1184889562926838573, 49914141857616862435
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OFFSET
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0,3
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FORMULA
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G.f.: exp(Sum_{k>0} sigma_k(k)x^k/k) . - Michael Somos Feb 15 2006
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PROGRAM
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(PARI) {a(n)=if(n<0, 0, polcoeff( exp(sum(k=1, n, sigma(k, k)*x^k/k, x*O(x^n))), n))} /* Michael Somos Feb 15 2006 */
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CROSSREFS
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Adjacent sequences: A023878 A023879 A023880 this_sequence A023882 A023883 A023884
Sequence in context: A058107 A023879 A084565 this_sequence A067111 A051549 A066780
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KEYWORD
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nonn
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AUTHOR
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Olivier Gerard (olivier.gerard(AT)gmail.com)
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