A012221 sech(arctan(arcsinh(x)))=1-1/2!*x^2+17/4!*x^4-769/6!*x^6+66401/8!*x^8...

1, -1, 17, -769, 66401, -9313281, 1927198833, -551835917697, 208856369686977, -100945109069282817, 60655475821737151953, -44346899335054478649345, 38762487400695339770533665

Offset

0,3

Links

Table of n, a(n) for n=0..12.

Crossrefs

Sequence in context: A360647 A355495 A368492 * A012144 A265190 A308490

Adjacent sequences: A012218 A012219 A012220 * A012222 A012223 A012224

Keyword

sign

Author

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

Status

approved