Theta series of D_13 lattice.

Terms

a(0) =1a(1) =312a(2) =11466a(3) =116688a(4) =535704a(5) =1899664a(6) =5043376a(7) =12066912a(8) =24443978a(9) =48210760a(10) =83323344a(11) =145532816a(12) =227110416a(13) =363737712a(14) =531517376a(15) =800145632a(16) =1104376728a(17) =1594656544a(18) =2114015514a(19) =2931991920a(20) =3779027408a(21) =5091783840a(22) =6365016528a(23) =8409556064a(24) =10285042352a(25) =13266026280a(26) =15994749968