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A012800 sech(sec(x)*tan(x))=1-1/2!*x^2-15/4!*x^4-177/6!*x^6+8225/8!*x^8... 0
1, -1, -15, -177, 8225, 1259231, 82092945, -6743602257, -3731314041535, -658546620230977, 68462273756819505, 102601344100683911439, 37004621343746850934625, -3605666448860960629195873 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[Sech[Sec[x]Tan[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Jul 02 2017 *)
CROSSREFS
Sequence in context: A081043 A155000 A009146 * A016216 A244604 A001717
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved

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Last modified June 22 06:03 EDT 2024. Contains 373565 sequences. (Running on oeis4.)