A012122 sech(arcsin(arcsinh(x)))=1-1/2!*x^2+5/4!*x^4-109/6!*x^6+4073/8!*x^8...

1, -1, 5, -109, 4073, -295161, 30105261, -4622444709, 920180967249, -244553774342769, 80285311139524821, -32887829518696856925, 16096767138947015536185, -9423401435342942243589225

Offset

0,3

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Sech[ArcSin[ArcSinh[x]]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Mar 19 2016 *)

Crossrefs

Sequence in context: A012121 A371882 A014180 * A012091 A322896 A296743

Adjacent sequences: A012119 A012120 A012121 * A012123 A012124 A012125

Keyword

sign

Author

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

Status

approved