A012552 Expansion of e.g.f. sec(sinh(x)*tan(x)) (only even powers).

1, 0, 12, 360, 21392, 2157120, 312620352, 62372069760, 16405335464192, 5496449323898880, 2285903378752576512, 1155546066959150254080, 697824091645377743654912, 496179920290601448240168960, 410314828419985666622333140992, 390461773708086832234701364101120, 423666204589884957176351804087140352

Offset

0,3

Links

Table of n, a(n) for n=0..16.

Example

E.g.f. = 1 + 12/4!*x^4 + 360/6!*x^6 + 21392/8!*x^8 + ...

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Sec[Sinh[x]Tan[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Nov 12 2021 *)

Crossrefs

Sequence in context: A327986 A279182 A002674 * A393977 A012385 A012430

Adjacent sequences: A012549 A012550 A012551 * A012553 A012554 A012555

Keyword

nonn

Author

Patrick Demichel

Extensions

a(14)-a(16) from Stefano Spezia, Dec 27 2025

Status

approved