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A012169
sech(tan(arcsinh(x)))=1-1/2!*x^2+1/4!*x^4-1/6!*x^6+449/8!*x^8...
0
1, -1, 1, -1, 449, -31681, 3077185, -445157441, 87981830785, -22627780368001, 7353703042163585, -2948527179059299201, 1429774747400938052161, -824792570907860638058561, 558247886671770078618138049
OFFSET
0,5
CROSSREFS
Sequence in context: A283791 A036945 A201182 * A093402 A012062 A339978
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved