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Search: id:A002039
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| A002039 |
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Related to partitions (g.f. is inverse to A000203).
(Formerly M2465 N0979)
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+0
2
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| 1, 3, 5, 10, 25, 64, 160, 390, 940, 2270, 5515, 13440, 32735, 79610, 193480, 470306, 1143585, 2781070, 6762990, 16445100, 39987325, 97232450, 236432060, 574915770, 1397981470, 3399360474, 8265943685, 20099618590, 48874630750
(list; graph; listen)
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OFFSET
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0,2
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
J. M. Gandhi, On numbers related to partitions of a number, Amer. Math. Monthly, 76 (1969), 1033-1036.
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LINKS
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Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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FORMULA
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G.f.: -q/(Sum_{k>0} k(-q)^k/(1-(-q)^k)) = 1/(log(f(q))') where f(-q)=Product_{k>0} (1-q^k) is one of Ramanujan's theta functions. - Michael Somos, Apr 08 2003
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PROGRAM
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(PARI) a(n)=polcoeff(1/log(eta(-x+x^2*O(x^n)))', n)
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CROSSREFS
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Cf. A002040, A000203.
Sequence in context: A018005 A080522 A132332 this_sequence A007695 A011969 A003187
Adjacent sequences: A002036 A002037 A002038 this_sequence A002040 A002041 A002042
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KEYWORD
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nonn,nice,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Simon Plouffe (simon.plouffe(AT)gmail.com)
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