Theta series of lattice D20+.

Terms

a(0) =1a(1) =0a(2) =760a(3) =0a(4) =77560a(5) =524288a(6) =2508000a(7) =10485760a(8) =34729720a(9) =99614720a(10) =259114704a(11) =608174080a(12) =1327461600a(13) =2739404800a(14) =5341699520a(15) =9921626112a(16) =17701924600a(17) =30592204800a(18) =51294999960a(19) =83277905920a(20) =131880275664