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 A012466 E.g.f. sec(arctan(x)^2) (even powers only). 1
 1, 0, 12, -480, 37968, -4773120, 878319552, -222512349696, 74262725323008, -31578556041732096, 16666719859336276992, -10690478515516973015040, 8190555666463900906475520, -7387658525325188387856384000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS EXAMPLE sec(arctan(x)^2) = =1+12/4!*x^4-480/6!*x^6+37968/8!*x^8+-... MATHEMATICA With[{nn=30}, Take[CoefficientList[Series[Sec[ArcTan[x]^2], {x, 0, nn}], x]Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Jan 12 2013 *) CROSSREFS Sequence in context: A012465 A012394 A012686 * A229634 A196704 A175322 Adjacent sequences:  A012463 A012464 A012465 * A012467 A012468 A012469 KEYWORD sign AUTHOR Patrick Demichel (patrick.demichel(AT)hp.com) STATUS approved

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Last modified October 14 08:54 EDT 2019. Contains 327995 sequences. (Running on oeis4.)