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A012645
sech(arcsinh(x)*cos(x))=1-1/2!*x^2+21/4!*x^4-765/6!*x^6+53193/8!*x^8...
0
1, -1, 21, -765, 53193, -6008025, 993328413, -226691205013, 68261145008657, -26216583047151921, 12507068079360896165, -7255577391165958142893, 5029681350011635244424921, -4106028806747521109741788425
OFFSET
0,3
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[Sech[ArcSinh[x]Cos[x]], {x, 0, nn}], x] Range[ 0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, May 15 2022 *)
CROSSREFS
Sequence in context: A143002 A062755 A012850 * A220069 A028469 A295845
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved