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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

%I

%S 1,0,-3,-30,-63,12540,602877,6625710,-1991169183,-241970036520,

%T -7540177734243,2917041754949850,699983161534169697,

%U 46722975483964508820,-21334067257986056115363,-8882421213380429461235610,-1081286159351846822872767423

%N sech(log(cos(x)))=1-3/4!*x^4-30/6!*x^6-63/8!*x^8+12540/10!*x^10...

%F 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

%t 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 *)

%Y Cf. A012003, A012007, A012008.

%K sign

%O 0,3

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

%E More terms from Harvey P. Dale, Dec 16 2011

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Last modified January 24 17:16 EST 2022. Contains 350565 sequences. (Running on oeis4.)