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A012779 Expansion of e.g.f.: sech(sec(x)*log(x+1))=1-1/2!*x^2+3/3!*x^3-18/4!*x^4+60/5!*x^5... 0
1, 0, -1, 3, -18, 60, -180, -1050, 24192, -308952, 3131760, -23742840, 62587272, 2606501040, -75839636600, 1415140435800, -20144425867712, 187207018203392, 730860552463104, -93674690778135744 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..19.

MATHEMATICA

With[{nn=20}, CoefficientList[Series[Sech[Sec[x]Log[x+1]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Apr 17 2016 *)

CROSSREFS

Sequence in context: A139362 A012763 A006011 * A327768 A074439 A299031

Adjacent sequences: A012776 A012777 A012778 * A012780 A012781 A012782

KEYWORD

sign

AUTHOR

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

EXTENSIONS

Definition clarified by Harvey P. Dale, Apr 17 2016

STATUS

approved

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Last modified November 29 08:40 EST 2022. Contains 358422 sequences. (Running on oeis4.)