A139134 a(n) = n-th derivative of Sec(Exp(z)-1) at z=0.

1, 0, 1, 3, 12, 65, 417, 3094, 26243, 250371, 2652754, 30910935, 392895789, 5409783392, 80214503397, 1274329677391, 21594115259540, 388790596531173, 7411710847692157, 149142571391245758, 3159081458947418511

Offset: 0

Author

Richard Chapling (r.chappers(AT)gmail.com), Jun 05 2008

Keywords

• easy
• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..100

Crossrefs

Cf. A080832.

Programs

Mathematica

Table[D[Sec[Exp[x] - 1], {x, n}] /. x -> 0, {n, 0, 30}]

Formula

E.G.F. = sec(exp(z)-1)

a(n) ~ 2*n!/((2+Pi)*log((2+Pi)/2)^(n+1)). - Vaclav Kotesovec, Sep 25 2013

Extensions

Typo in Mathematica program corrected by Vincenzo Librandi, Sep 26 2013