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Search: id:A088436
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| A088436 |
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Number of permutations in the symmetric group S_n that have exactly one transposition in their cycle decomposition. |
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+0
2
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| 0, 1, 3, 6, 30, 225, 1575, 12180, 109620, 1100925, 12110175, 145259730, 1888376490, 26438216805, 396573252075, 6345155817000, 107867648889000, 1941617990136825, 36890741812599675, 737814829704702750
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OFFSET
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1,3
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REFERENCES
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Ch. A. Charalambides, Enumerative Combinatorics, Chapman & Hall/CRC, Boca Raton, Florida, 2002, p. 189, Exercise 19 for k=1. With (-1)^k omitted.
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FORMULA
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a(n)=n!*sum(((-1)^j)/(j!*2^j),j=0..floor(n/2)-k)/(k!*2^k), n>=1.
E.g.f.: x^2/(1-x)/2*exp(-x^2/2). - Vladeta Jovovic (vladeta(AT)eunet.rs), Nov 09 2003
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CROSSREFS
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Cf. A000266, A027616, A000240.
Sequence in context: A090932 A157534 A133799 this_sequence A088506 A061137 A012280
Adjacent sequences: A088433 A088434 A088435 this_sequence A088437 A088438 A088439
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KEYWORD
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nonn
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AUTHOR
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Yuval Dekel (dekelyuval(AT)hotmail.com), Nov 09 2003
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EXTENSIONS
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More terms from Wolfdieter Lang (wolfdieter.lang(AT)physik.uni-karlsruhe.de), Feb 22 2008
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