A009422 - OEIS

A009422

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

0, 0, 2, -6, 30, -160, 1084, -8316, 74456, -749184, 8474240, -106035424, 1459781056, -21914009728, 356711937152, -6258266154752, 117778607150592, -2366994133647360, 50601711980789760, -1146653711692951552

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OFFSET

0,3

LINKS

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

FORMULA

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

MATHEMATICA

Log[ 1+x ]*Log[ 1+Tan[ x ] ]

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

CROSSREFS

Sequence in context: A357582 A218940 A005432 * A057221 A180892 A366266

Adjacent sequences: A009419 A009420 A009421 * A009423 A009424 A009425

KEYWORD

sign,easy

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

STATUS

approved