A009310 Expansion of log(1+log(1+tan(x))).

0, 1, -2, 9, -51, 384, -3506, 38126, -479770, 6872392, -110410296, 1967181840, -38502498592, 821352161200, -18969587297792, 471608373782864, -12558441874756176, 356636706706414848, -10759204665600245888

Offset

0,3

Links

Table of n, a(n) for n=0..18.

Formula

a(n) ~ (n-1)! * (-1)^(n+1) / (arctan(1-exp(-1))^n). - Vaclav Kotesovec, Jan 22 2015

Mathematica

Log[ 1+Log[ 1+Tan[ x ] ] ]
CoefficientList[Series[Log[1 + Log[1 + Tan[x]]], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 22 2015 *)

Crossrefs

Sequence in context: A026945 A246464 A355397 * A091319 A193465 A003584

Adjacent sequences: A009307 A009308 A009309 * A009311 A009312 A009313

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved