Expansion of e.g.f. x/cos(x)*exp(x/cos(x)).

Terms

a(0) =1a(1) =2a(2) =6a(3) =28a(4) =120a(5) =726a(6) =4424a(7) =31928a(8) =249984a(9) =2131690a(10) =20027392a(11) =199240020a(12) =2162269824a(13) =24676708798a(14) =302660939520