A009369 - OEIS

A009369

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

0, 1, -1, 1, -8, 45, -301, 2357, -21608, 223769, -2602081, 33484713, -473210528, 7282225093, -121272163741, 2172791685469, -41680241726768, 852337358029617, -18510436676621281, 425474580069715025, -10319766893265298328

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OFFSET

0,5

LINKS

Table of n, a(n) for n=0..20.

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

CROSSREFS

Sequence in context: A289896 A367435 A006887 * A120044 A328885 A002686

Adjacent sequences: A009366 A009367 A009368 * A009370 A009371 A009372

KEYWORD

sign,easy

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

STATUS

approved