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A013528 Numerator of [x^(2n)] of the Taylor series sech(cosec(x)-cot(x)) = 1 -x^2/8 -x^4/128 +x^6/15360 +19*x^8/294912 +25031*x^10/3715891200+... . 1

%I

%S 1,-1,-1,1,19,25031,18421,-622177,-283401163,-24826632949,-2243454779,

%T 4882905709651,43798187793808543,-46704901267812186793,

%U -5325187532598955153807

%N Numerator of [x^(2n)] of the Taylor series sech(cosec(x)-cot(x)) = 1 -x^2/8 -x^4/128 +x^6/15360 +19*x^8/294912 +25031*x^10/3715891200+... .

%C The e.g.f. related to x/2, sech(cosec(x)-cot(x)) = 1 -1*x^2/(2^2*2!) -3*x^4*(2^4*4!) +3*x^6/(2^6*6!) +665*x^8/(2^8*8!) +.. is (up to signs) apparently provided by A009011.

%H G. C. Greubel, <a href="/A013528/b013528.txt">Table of n, a(n) for n = 0..200</a>

%t Numerator[Take[CoefficientList[Series[Sech[Csc[x] - Cot[x]], {x,0,50}], x], {1, -1, 2}]] (* _G. C. Greubel_, Nov 12 2016 *)

%K sign,frac

%O 0,5

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

%E Name edited by _R. J. Mathar_, Dec 20 2011

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Last modified March 5 16:12 EST 2021. Contains 341825 sequences. (Running on oeis4.)