A009646 Expansion of tan(log(1+x))/cos(x).

0, 1, -1, 7, -24, 175, -1155, 10477, -100968, 1147901, -14251005, 197307251, -2969362176, 48613104059, -856679861583, 16197513235945, -326703748009200, 7005133086139705, -159063002342367705, 3813308579832354079

Offset

0,4

Links

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

Formula

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

Mathematica

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

Crossrefs

Sequence in context: A009643 A108095 A223007 * A293489 A009650 A111753

Adjacent sequences: A009643 A009644 A009645 * A009647 A009648 A009649

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved