A012018 sech(sin(tan(x)))=1-1/2!*x^2+1/4!*x^4+47/6!*x^6+897/8!*x^8...

1, -1, 1, 47, 897, 26911, 2176769, 269558351, 38463601409, 6445724731199, 1297792574780417, 307585734223517551, 82426762826906376833, 23816926512873022989919, 6844111898535212011277057

Offset

0,4

Links

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

Crossrefs

Sequence in context: A262120 A032626 A009054 * A010963 A234354 A161692

Adjacent sequences: A012015 A012016 A012017 * A012019 A012020 A012021

Keyword

sign

Author

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

Status

approved