A009372 Expansion of log(1+tan(x))/cos(x).

0, 1, -1, 7, -20, 145, -781, 6711, -55040, 578465, -6372241, 81400295, -1118247140, 17017477425, -278763221101, 4944906503959, -93847119338720, 1903841305391425, -41033336868850561, 937270802152757703

Offset

0,4

Links

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

Formula

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

Mathematica

Log[ 1+Tan[ x ]]/Cos[ x ]
CoefficientList[Series[Log[1 + Tan[x]]*Sec[x], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 23 2015 *)

Crossrefs

Sequence in context: A009370 A299091 A299873 * A051102 A299009 A299800

Adjacent sequences: A009369 A009370 A009371 * A009373 A009374 A009375

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved