A012133 sech(arcsin(tanh(x)))=1-1/2!*x^2+9/4!*x^4-201/6!*x^6+8369/8!*x^8...

1, -1, 9, -201, 8369, -559601, 54852729, -7411089401, 1320161221089, -299803443573601, 84543945702681449, -28984920596097196201, 11872728882101557841809, -5726623333843769342341201

Offset

0,3

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Sech[ArcSin[Tanh[x]]], {x, 0, nn}], x] Range[ 0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Sep 21 2022 *)

Crossrefs

Sequence in context: A052145 A012061 A012168 * A012038 A012108 A251587

Adjacent sequences: A012130 A012131 A012132 * A012134 A012135 A012136

Keyword

sign

Author

Patrick Demichel (patrick.demichel(AT)hp.com)

Status

approved