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A013302 cosh(log(x+1)-arctanh(x))=1+3/4!*x^4+90/6!*x^6+4725/8!*x^8... 2
1, 0, 3, 90, 4725, 396900, 49116375, 8428369950, 1917454163625, 558800927685000, 203054287097536875, 90020733946574681250, 47828015945815128148125, 30001210002374944020187500 (list; graph; refs; listen; history; internal format)
OFFSET

0,3

COMMENTS

Number of degree-2n permutations without odd cycles and with even number of even cycles. E.g.f.: (2-x^2)/(2*sqrt(1-x^2)). - Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 10 2007

CROSSREFS

Cf. A013299.

Sequence in context: A047686 A013304 A013298 * A013303 A166334 A168408

Adjacent sequences:  A013299 A013300 A013301 * A013303 A013304 A013305

KEYWORD

nonn

AUTHOR

Patrick Demichel (dml(AT)hpfrcu03.france.hp.com)

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Last modified February 17 18:38 EST 2012. Contains 206074 sequences.