A102072 E.g.f. sec(arcsinh(x)) = cosec(arccosh(x)) (even powers only).

1, 1, 1, 25, -415, 35825, -3356575, 492769225, -96314333375, 24701457990625, -8006683308349375, 3204344303824405625, -1551453429875871169375, 893896220277392770140625, -604413346665043743464609375

Offset

0,4

Links

Table of n, a(n) for n=0..14.

Example

sec(arcsinh(x)) = 1 + x^2/2 + x^4/4! + 25x^6/6! - 415x^8/8! +...
sech(arcsin(x)) = 1 - x^2/2 + x^4/4! - 25x^6/6! - 415x^8/8! -...

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Sec[ArcSinh[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Aug 15 2016 *)

Crossrefs

Sequence in context: A025980 A025978 A028037 * A022845 A023952 A025991

Adjacent sequences: A102069 A102070 A102071 * A102073 A102074 A102075

Keyword

sign

Author

Ralf Stephan, Dec 31 2004

Status

approved