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%I #14 Aug 16 2018 13:25:16
%S -2,118,-267122,3801437638,-188997287445602,24300893634392843158,
%T -6725983870126469414416082,3540538990952328979449335176678,
%U -3241779510843677923729210281115258562
%N Coefficient of x^(4*n+2) in e.g.f. arcsinh(cos(x) - cosh(x)).
%H Robert Israel, <a href="/A013476/b013476.txt">Table of n, a(n) for n = 0..112</a>
%e -(2/2!)*x^2 + (118/6!)*x^6 - (267122/10!)*x^10 + (3801437638/14!)*x^14 - ...
%p S:= series(arcsinh(cos(x)-cosh(x)),x,103):
%p seq(coeff(S,x,4*n+2)*(4*n+2)!,n=0..25); # _Robert Israel_, Aug 16 2018
%K sign
%O 0,1
%A Patrick Demichel (patrick.demichel(AT)hp.com)
%E Missing a(0)=-2 inserted, more terms, and title improved by _Sean A. Irvine_, Aug 07 2018
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