A009370 Expansion of log(1+tan(x))*cosh(x).

0, 1, -1, 7, -20, 125, -721, 5731, -49440, 505529, -5716921, 72560255, -1009426340, 15366052533, -253286287801, 4501151653979, -85717611666720, 1742059862631537, -37625735499057361, 860703388428813303

Offset

0,4

Links

Table of n, a(n) for n=0..19.

Formula

a(n) ~ (n-1)! * (-1)^(n+1) * (exp(-Pi/4) + exp(Pi/4)) * 2^(2*n-1) / Pi^n. - Vaclav Kotesovec, Jan 23 2015

Mathematica

With[{nn=20}, CoefficientList[Series[Log[1+Tan[x]]*Cosh[x], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, May 25 2013 *)

Crossrefs

Sequence in context: A265657 A298214 A299346 * A299091 A299873 A009372

Adjacent sequences: A009367 A009368 A009369 * A009371 A009372 A009373

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved