a(n) = C(n^2) - C(n), where C(n) is Chowla's function (A048050).

Terms

a(0) =0a(1) =2a(2) =3a(3) =12a(4) =5a(5) =49a(6) =7a(7) =56a(8) =36a(9) =109a(10) =11a(11) =243a(12) =13a(13) =193a(14) =169a(15) =240a(16) =17a(17) =502a(18) =19a(19) =539a(20) =289a(21) =433a(22) =23a(23) =1039a(24) =150a(25) =589a(26) =351a(27) =955a(28) =29a(29) =1879