Glaisher's function theta(n) (18 squares version).

Terms

a(0) =0a(1) =-7a(2) =128a(3) =-975a(4) =4608a(5) =-16340a(6) =48384a(7) =-124303a(8) =281600a(9) =-583746a(10) =1146240a(11) =-2125108a(12) =3691008a(13) =-6151880a(14) =10055424a(15) =-15914895a(16) =24136704a(17) =-35748899a(18) =52583040a(19) =-75877938a(20) =105994240a(21) =-145580124a(22) =200279808a(23) =-272040500a(24) =359036928a(25) =-468767690a(26) =615599360