Theta series of square lattice with respect to edge.

Terms

a(0) =2a(1) =4a(2) =2a(3) =4a(4) =4a(5) =0a(6) =6a(7) =4a(8) =0a(9) =4a(10) =4a(11) =4a(12) =2a(13) =4a(14) =0a(15) =4a(16) =8a(17) =0a(18) =4a(19) =0a(20) =2a(21) =8a(22) =4a(23) =0a(24) =4a(25) =4a(26) =0a(27) =4a(28) =4a(29) =4