Expansion of e.g.f. arcsinh(exp(x) - sec(x)).

Terms

a(0) =0a(1) =1a(2) =0a(3) =0a(4) =-4a(5) =0a(6) =0a(7) =0a(8) =-1104a(9) =-5040a(10) =0a(11) =184800a(12) =-1784704a(13) =-39948480a(14) =-201801600a(15) =2969366400a(16) =24788541696a(17) =-621491320320