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A012153 sec(tan(tan(x)))=1+1/2!*x^2+21/4!*x^4+1053/6!*x^6+96905/8!*x^8... 0

%I #6 Jun 19 2021 10:00:03

%S 1,1,21,1053,96905,14216409,3045819741,897606889013,348348521840273,

%T 172224469448231985,105685328498514238501,78822199814116989651661,

%U 70223663543654715642543129,73659278933239564262294052361

%N sec(tan(tan(x)))=1+1/2!*x^2+21/4!*x^4+1053/6!*x^6+96905/8!*x^8...

%t With[{nn=30},Take[CoefficientList[Series[Sec[Tan[Tan[x]]],{x,0,nn}],x] Range[ 0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Jun 19 2021 *)

%K nonn

%O 0,3

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

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Last modified February 27 04:33 EST 2024. Contains 370362 sequences. (Running on oeis4.)