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A012062
sech(sin(arctanh(x)))=1-1/2!*x^2+1/4!*x^4-1/6!*x^6+449/8!*x^8...
0
1, -1, 1, -1, 449, 45119, 6456385, 1205597119, 290952557185, 88525830844799, 33241403103347585, 15120239602445366399, 8199386238595549354561, 5228782379279703730965439, 3875091407041220683147290049
OFFSET
0,5
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[Sech[Sin[ArcTanh[x]]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Sep 15 2013 *)
CROSSREFS
Sequence in context: A201182 A012169 A093402 * A339978 A351947 A079659
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved