A012609 Expansion of e.g.f. sech(arcsinh(x)*arcsin(x)) in powers of x^4.

1, -12, 3472, -20044992, -47937777408, -20305698249280512, -2854719816291959009280, -1250271985277826533770444800, -852308886538376231161133484933120, -1020041468410487908146642041792342261760, -1902990477565541776130152995745141108333608960

Offset

0,2

Links

Andrew Howroyd, Table of n, a(n) for n = 0..50

Example

1 - 12/4!*x^4 + 3472/8!*x^8 - 20044992/12!*x^12 ...

Prog

(PARI) a(n)={my(x=x+O(x*x^(4*n))); polcoef(serlaplace(1/cosh(asinh(x)*asin(x))), 4*n)} \\ Andrew Howroyd, Nov 05 2019

Crossrefs

Sequence in context: A077299 A077749 A077297 * A159395 A272093 A099186

Adjacent sequences: A012606 A012607 A012608 * A012610 A012611 A012612

Keyword

sign

Author

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

Extensions

Terms a(8) and beyond from Andrew Howroyd, Nov 05 2019

Status

approved