A009376 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A009376

Expansion of log(1 + tan(x)*exp(x)).

0, 1, 1, 1, -2, 5, 6, 131, -552, 3065, -10934, 216511, -1516052, 13359125, -110965074, 1704426491, -17363056752, 210045171185, -2585510594414, 41595973502071, -563643499480652, 8626434032607245, -136389526384050954

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,5

LINKS

Table of n, a(n) for n=0..22.

FORMULA

a(n) ~ (n-1)! * (-1)^(n+1) / r^n, where r = 1.306326940423079236174356658440682315179068358... is the root of the equation tan(r)/exp(r) = 1. - Vaclav Kotesovec, Jan 24 2015

MATHEMATICA

CoefficientList[Series[Log[1 + E^x*Tan[x]], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 24 2015 *)

CROSSREFS

Sequence in context: A111190 A244434 A176007 * A231364 A025123 A071791

Adjacent sequences: A009373 A009374 A009375 * A009377 A009378 A009379

KEYWORD

sign,easy

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

First Mathematica program deleted by Harvey P. Dale, Dec 16 2024

STATUS

approved