Theta series of hexagonal close-packing with respect to triangle between tetrahedra.

Terms

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