%I #9 Aug 02 2015 21:09:16
%S 1,-12,1568,6840768,-41485549312,-616649036623872,
%T 51689032519042469888,309411873154808535072768
%N sech(sec(x)-sech(x))=1-12/4!*x^4+1568/8!*x^8+6840768/12!*x^12...
%p A013515 := proc(n)
%p sech(sec(x)-sech(x)) ;
%p coeftayl( %,x=0,4*n) ;
%p %*(4*n)! ;
%p end proc: # _R. J. Mathar_, Dec 16 2011
%K sign
%O 0,2
%A Patrick Demichel (patrick.demichel(AT)hp.com)
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