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Search: id:A130639
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| A130639 |
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Number of degree-2n permutations without even cycles and such that number of cycles of size 2k-1 is even (or zero) for every k. |
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+0
1
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| 1, 1, 1, 41, 1121, 80977, 5073377, 984765497, 131026429249, 45819745767329, 9199822716980033, 5303459200225973833, 1646226697154555000993, 1377111876294420026771441, 574027598120143165861124641
(list; graph; listen)
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OFFSET
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0,4
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FORMULA
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E.g.f.: Product_{k>0} cosh(x^(2*k-1)/(2*k-1)).
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EXAMPLE
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a(2)=1 because we have (1)(2)(3)(4).
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MAPLE
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g:=product(cosh(x^(2*k-1)/(2*k-1)), k=1..40): gser:=series(g, x=0, 35): seq(factorial(2*n)*coeff(gser, x, 2*n), n=0..14); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 25 2007
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CROSSREFS
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Cf. A060307.
Adjacent sequences: A130636 A130637 A130638 this_sequence A130640 A130641 A130642
Sequence in context: A059762 A069362 A016093 this_sequence A014937 A118451 A094455
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KEYWORD
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easy,nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)Eunet.yu), Aug 11 2007
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 25 2007
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