Numbers k such that sigma(k^2 + 1) == 0 (mod k).

Terms

a(0) =1a(1) =2a(2) =3a(3) =9a(4) =12a(5) =21a(6) =33a(7) =72a(8) =93a(9) =196a(10) =228a(11) =252a(12) =360a(13) =475a(14) =850a(15) =1458a(16) =1725a(17) =1752a(18) =2100a(19) =2241a(20) =2584a(21) =3007a(22) =3404a(23) =4347a(24) =4743a(25) =5544a(26) =5720a(27) =6555a(28) =6600a(29) =9909