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A102073 Numerators of e.g.f. sec(arccosh(x)) = cosec(arcsinh(x)). 1
1, -1, 220, -830, 51280, -24271600, 2978372800, -72656038000, 6574942704928000, -369025338813664000, 439973927875730560000, -16173932272478277440000, 8586787143256164544000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..13.

EXAMPLE

sec(arccosh(x)) = 1/x + x/3 - 1/3*x^3/3! + 220/63*x^5/5! - ...

MATHEMATICA

terms = 13; s = -1/x + Csc[ArcSinh[x]] + O[x]^(2 terms) // Normal;

CoefficientList[s, x] * Range[0, 2 terms - 1]! // DeleteCases[#, 0]& // Numerator (* Jean-Fran├žois Alcover, Jul 23 2017 *)

CROSSREFS

Denominators are in A102074.

Sequence in context: A257361 A258538 A257354 * A234969 A002025 A260086

Adjacent sequences:  A102070 A102071 A102072 * A102074 A102075 A102076

KEYWORD

sign,frac

AUTHOR

Ralf Stephan, Dec 31 2004

STATUS

approved

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Last modified November 29 21:32 EST 2021. Contains 349416 sequences. (Running on oeis4.)