A012692 sech(tanh(x)*cos(x))=1-1/2!*x^2+25/4!*x^4-1057/6!*x^6+81905/8!*x^8...

1, -1, 25, -1057, 81905, -10280289, 1887120585, -476966767617, 158890850697185, -67468163508862017, 35571148438980847225, -22799419589275221917281, 17459463801481355245128145

Offset

0,3

Links

Table of n, a(n) for n=0..12.

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Sech[Tanh[x]Cos[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Apr 13 2019 *)

Crossrefs

Sequence in context: A367974 A167257 A346160 * A193121 A246923 A066852

Adjacent sequences: A012689 A012690 A012691 * A012693 A012694 A012695

Keyword

sign

Author

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

Status

approved