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Search: id:A007322
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| A007322 |
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Number of functors of degree n from free Abelian groups to Abelian groups.
(Formerly M4231)
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+0
3
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| 1, 6, 39, 320, 3281, 40558, 586751, 9719616, 181353777, 3762893750, 85934344775, 2141853777856, 57852105131809, 1683237633305502, 52483648929669119, 1745835287515739328, 61712106494672572641, 2309989101145068446502
(list; graph; listen)
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OFFSET
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1,2
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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).
H. J. Baues, Quadratic functors and metastable homotopy, Jnl. Pure and Applied Algebra, 91 (1994), 49-107.
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FORMULA
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Binomial transform of A101370. - Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 17 2006
a(n) = (1/n!)*Sum_{k=1..n} (-1)^(n-k)*Stirling1(n+1,k+1)*A000670(k)^2. - Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 17 2006
G.f.: (1/(1-x))*Sum_{m>0,n>0} Sum_{j=1..n} (-1)^(n-j)*binomial(n,j)*((1-x)^(-j)-1)^m. - Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 17 2006
Partial sums of A120733. - Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 21 2006
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CROSSREFS
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Sequence in context: A135890 A067273 A137972 this_sequence A058191 A113347 A031972
Adjacent sequences: A007319 A007320 A007321 this_sequence A007323 A007324 A007325
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KEYWORD
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nonn,nice
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AUTHOR
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Don Zagier (don.zagier(AT)mpim-bonn.mpg.de), Apr 11 1994
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EXTENSIONS
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More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 17 2006
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