A128274 Absolute values of numerators of series expansion of cosh(x)/sqrt((cosh(x))^2+(sinh(x))^2) about 0 (even-indexed coefficients only).

1, 1, 17, 721, 58337, 7734241, 218014151, 419784870961, 153563504618177, 10300599833780983, 2486497854930863041, 30262124466958766778001, 3711710439292601861342231, 26350476755161831091778460321, 31166629149666821954776191205937, 45673109693364177065089340171611

Offset: 0

Author

Artur Jasinski, Feb 22 2007

Keywords

• nonn

Crossrefs

Cf. A012085, A012193, A128275.

Programs

Mathematica

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

Extensions

Offset 0 and more terms from Alois P. Heinz, Apr 08 2021