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A012691 sec(tanh(x)*cos(x))=1+1/2!*x^2-15/4!*x^4+57/6!*x^6+13825/8!*x^8... 0
1, 1, -15, 57, 13825, -869711, -32509455, 15341387817, -1155396011135, -466737414209183, 173446757621320305, 4992444359346419481, -27407671098104949154175, 8541081671506270503758353 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..13.

MATHEMATICA

With[{nn=30}, Take[CoefficientList[Series[Sec[Tanh[x]Cos[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Sep 06 2015 *)

CROSSREFS

Sequence in context: A240152 A261419 A183942 * A020187 A261798 A022287

Adjacent sequences:  A012688 A012689 A012690 * A012692 A012693 A012694

KEYWORD

sign

AUTHOR

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

STATUS

approved

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Last modified August 20 16:58 EDT 2017. Contains 290836 sequences.