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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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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; refs; listen; history; internal format)
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OFFSET
| 1,2
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REFERENCES
| H. J. Baues, Quadratic functors and metastable homotopy, Jnl. Pure and Applied Algebra, 91 (1994), 49-107.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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FORMULA
| 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
| Sequence in context: A067273 A187117 A137972 * A058191 A113347 A031972
Adjacent sequences: A007319 A007320 A007321 * A007323 A007324 A007325
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KEYWORD
| nonn,nice
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AUTHOR
| Don Zagier (don.zagier(AT)mpim-bonn.mpg.de), Apr 11 1994
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EXTENSIONS
| More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 17 2006
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