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 A012009 sech(log(cos(x)))=1-3/4!*x^4-30/6!*x^6-63/8!*x^8+12540/10!*x^10... 1
 1, 0, -3, -30, -63, 12540, 602877, 6625710, -1991169183, -241970036520, -7540177734243, 2917041754949850, 699983161534169697, 46722975483964508820, -21334067257986056115363, -8882421213380429461235610, -1081286159351846822872767423 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS FORMULA E.g.f. sech(log(cos(x)) = 2*cos(x)/(1+cos^2(x)) is the reciprocal of the e.g.f. of A012007. - Peter Bala, Dec 02 2011 MATHEMATICA With[{nn=40}, Take[CoefficientList[Series[Sech[Log[Cos[x]]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Dec 16 2011 *) CROSSREFS Cf. A012003, A012007, A012008. Sequence in context: A061472 A132084 A208880 * A001800 A152767 A195029 Adjacent sequences:  A012006 A012007 A012008 * A012010 A012011 A012012 KEYWORD sign AUTHOR Patrick Demichel (patrick.demichel(AT)hp.com) EXTENSIONS More terms from Harvey P. Dale, Dec 16 2011 STATUS approved

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Last modified November 26 17:52 EST 2021. Contains 349343 sequences. (Running on oeis4.)