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A130648
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Number of degree-n permutations without even cycles and such that number of cycles of size 2k-1 is odd (or zero) for every k.
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0
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1, 1, 0, 3, 8, 25, 184, 721, 9904, 66753, 691088, 5973121, 84925048, 940427137, 12801319816, 186556383105, 3174772979936, 48489077948161, 842173637012896, 15359492773456129, 316965131969908072, 6368424993521096961
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,4
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FORMULA
| E.g.f.: Product_{k>0} (1+sinh(x^(2*k-1)/(2*k-1))).
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EXAMPLE
| a(3)=3 because we have (1)(2)(3), (123) and (132).
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MAPLE
| g:=product(1+sinh(x^(2*k-1)/(2*k-1)), k=1..30): gser:=series(g, x=0, 27): seq(factorial(n)*coeff(gser, x, n), n=0..24); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 24 2007
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CROSSREFS
| Cf. A060307.
Sequence in context: A004205 A097713 A009392 * A061812 A009452 A206141
Adjacent sequences: A130645 A130646 A130647 * A130649 A130650 A130651
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KEYWORD
| easy,nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 11 2007
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EXTENSIONS
| More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 24 2007
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