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A009639
E.g.f.: tan(log(1+tan(x))).
0
0, 1, -1, 6, -26, 206, -1666, 17476, -201256, 2686856, -39501256, 644639696, -11460605936, 221416107056, -4607717991696, 102865898480416, -2450540846322816, 62064658738621056, -1664916515878596736
OFFSET
0,4
FORMULA
a(n) ~ n! * (-1)^(n+1) * exp(Pi/2) / ((1 - 2*exp(Pi/2) + 2*exp(Pi)) * arctan(1 - exp(-Pi/2))^(n+1)). - Vaclav Kotesovec, Jan 23 2015
MATHEMATICA
With[{nn=20}, CoefficientList[Series[Tan[Log[1+Tan[x]]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Aug 28 2012 *)
CROSSREFS
Sequence in context: A053946 A211946 A027283 * A323868 A226980 A199591
KEYWORD
sign,easy
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
Definition clarified by Harvey P. Dale, Aug 28 2012
STATUS
approved