Expansion of e.g.f. 1/(1 - x*cos(x))^2.

Terms

a(0) =1a(1) =2a(2) =6a(3) =18a(4) =48a(5) =10a(6) =-1440a(7) =-17654a(8) =-153216a(9) =-1003950a(10) =-2787840a(11) =58057538a(12) =1483941888a(13) =22381115354a(14) =245730121728