A012477 arctanh(cos(x)*sin(x))=x-2/3!*x^3-40/5!*x^5+208/7!*x^7+64640/9!*x^9...

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

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: A281761 A370069 A359859 * A003760 A228240 A155977

Adjacent sequences: A012474 A012475 A012476 * A012478 A012479 A012480

Keyword

sign

Author

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

Status

approved