Expansion of e.g.f. z*(2*(exp(z) + 1)/(cosh(z) + cos(z)) - 1).

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =4a(5) =-5a(6) =-24a(7) =-98a(8) =-272a(9) =621a(10) =4960a(11) =31856a(12) =132672a(13) =-437593a(14) =-4893056a(15) =-42854160a(16) =-237969664a(17) =1026405753a(18) =14756156928a(19) =163699919104