A012169 sech(tan(arcsinh(x)))=1-1/2!*x^2+1/4!*x^4-1/6!*x^6+449/8!*x^8...

1, -1, 1, -1, 449, -31681, 3077185, -445157441, 87981830785, -22627780368001, 7353703042163585, -2948527179059299201, 1429774747400938052161, -824792570907860638058561, 558247886671770078618138049

Offset

0,5

Links

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

Crossrefs

Sequence in context: A283791 A036945 A201182 * A093402 A012062 A339978

Adjacent sequences: A012166 A012167 A012168 * A012170 A012171 A012172

Keyword

sign

Author

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

Status

approved