Number of solutions to 1 +- 4 +- 9 +- ... +- n^2 == 0 (mod n).

Terms

a(0) =1a(1) =0a(2) =2a(3) =4a(4) =6a(5) =0a(6) =10a(7) =48a(8) =32a(9) =0a(10) =94a(11) =344a(12) =370a(13) =0a(14) =1268a(15) =4608a(16) =3856a(17) =0a(18) =13798a(19) =55960a(20) =50090a(21) =0a(22) =182362a(23) =721952a(24) =690496a(25) =0a(26) =2485592a(27) =9586984a(28) =9256746a(29) =0