

A012477


arctanh(cos(x)*sin(x))=x2/3!*x^340/5!*x^5+208/7!*x^7+64640/9!*x^9...


0



1, 2, 40, 208, 64640, 986368, 652487680, 60911593472, 20973645824000, 6185783347314688, 1429441147870904320, 1203534317202507825152, 109702530161745707663360, 415034067689086640359211008
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OFFSET

0,2


LINKS

Table of n, a(n) for n=0..13.


FORMULA

Lim sup n>infinity a(n)/(2^(4*n+3)*(2*n)!/(Pi^2 + 4*(log(2+sqrt(3)))^2)^(n+1/2)) = 1.  Vaclav Kotesovec, Oct 24 2013


MATHEMATICA

Table[n!*SeriesCoefficient[ArcTanh[Cos[x]*Sin[x]], {x, 0, n}], {n, 1, 40, 2}] (* Vaclav Kotesovec, Oct 24 2013 *)


CROSSREFS

Sequence in context: A275547 A269544 A281761 * A003760 A228240 A155977
Adjacent sequences: A012474 A012475 A012476 * A012478 A012479 A012480


KEYWORD

sign


AUTHOR

Patrick Demichel (patrick.demichel(AT)hp.com)


STATUS

approved



