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A128274 Absolute values of numerators of series expansion of cosh(x)/sqrt((cosh(x))^2+(sinh(x))^2) about 0. 1
1, 1, 17, 721, 58337, 7734241, 218014151, 419784870961, 153563504618177, 10300599833780983 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..10.

MATHEMATICA

Series[Cosh[x]/(Sqrt[Cosh[x]^2 + Sinh[x]^2]), {x, 0, 20}]

cc=CoefficientList[Series[Sinh[x]/(Sqrt[Cosh[x]^2+Sinh[x]^2]), {x, -, 26}], x]; kk={}; Do[AppendTo[kk, Abs[Numerator[cc[[k]]]], {k, 2, Length[cc], 2]; kk

CROSSREFS

Cf. A012085, A012193.

Sequence in context: A012182 A012029 A012193 * A012085 A298306 A218423

Adjacent sequences:  A128271 A128272 A128273 * A128275 A128276 A128277

KEYWORD

nonn

AUTHOR

Artur Jasinski, Feb 22 2007

STATUS

approved

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Last modified March 23 18:13 EDT 2019. Contains 321433 sequences. (Running on oeis4.)