A013138 - OEIS

A013138

cos(tanh(x)+tan(x))=1-4/2!*x^2+16/4!*x^4-448/6!*x^6+14592/8!*x^8...

1, -4, 16, -448, 14592, -705536, 65245184, -5385535488, 910402060288, -124371776831488, 30930578556583936, -6638266678020931584, 2186545615284171964416, -694382737827711997181952

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..13.

MATHEMATICA

With[{nn=30}, Take[CoefficientList[Series[Cos[Tanh[x]+Tan[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Sep 21 2024 *)

CROSSREFS

Sequence in context: A000874 A061580 A037976 * A262546 A013006 A013001

Adjacent sequences: A013135 A013136 A013137 * A013139 A013140 A013141

KEYWORD

sign

AUTHOR

Patrick Demichel

STATUS

approved