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Search: id:A163190
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| A163190 |
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a(n) = Sum_{k=0..n} C(n,k)*sigma(n,k) for n>0 with a(0)=1. |
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+0
2
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| 1, 2, 13, 72, 722, 7808, 122538, 2097280, 43444163, 1000262656, 25997950850, 743008372736, 23312187863060, 793714773262336, 29197324076701082, 1152921975865606144, 48663045048486723204, 2185911559738696663040
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Definition: sigma(n,k)= sigma_k(n) = Sum_{d|n} d^k.
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FORMULA
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a(n) = Sum_{d|n} (1+d)^n for n>0 with a(0)=1.
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PROGRAM
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(PARI) {a(n)=if(n==0, 1, sumdiv(n, d, (1+d)^n))}
(PARI) {a(n)=if(n==0, 1, sum(k=0, n, binomial(n, k)*sigma(n, k)))}
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CROSSREFS
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Cf. A000203 (sigma).
Sequence in context: A128743 A097349 A109112 this_sequence A004027 A154357 A161130
Adjacent sequences: A163187 A163188 A163189 this_sequence A163191 A163192 A163193
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Jul 22 2009
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