Theta series of cubic lattice with respect to square.

Terms

a(0) =4a(1) =8a(2) =8a(3) =16a(4) =12a(5) =8a(6) =24a(7) =16a(8) =16a(9) =24a(10) =16a(11) =16a(12) =28a(13) =32a(14) =8a(15) =32a(16) =32a(17) =16a(18) =40a(19) =16a(20) =16a(21) =40a(22) =40a(23) =32a(24) =36a(25) =16a(26) =24a(27) =48a(28) =32a(29) =24