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%I #9 Aug 06 2012 10:36:36
%S 1,1,-7,121,-3823,186961,-12464695,967217161,-51115216735,
%T -15922673810399,12685061907297305,-7463929930799687399,
%U 4531120544938557395633,-3032728078954072676445839
%N E.g.f. sec(sin(arctan(x))) = 1/cos(x/sqrt(1+x^2)).
%F E.g.f.: 1/cos(x/sqrt(1+x^2)) = 1 + x^2/(G(0)) where G(k)= 2*(2*k+1)*(k+1)*(1+x^2) - x^2 + 2*(2*k+1)*(k+1)*x^2*(1+x^2)/G(k+1); (continued fraction, Euler's 1st kind, 1-step). - Sergei N. Gladkovskii, Aug 06 2012
%e sec(sin(arctan(x)))=1+1/2!*x^2-7/4!*x^4+121/6!*x^6-3823/8!*x^8...
%K sign
%O 0,3
%A Patrick Demichel (patrick.demichel(AT)hp.com)
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