Numbers k such that k+1 and sigma(k)+1 are both perfect squares.

Terms

a(0) =8a(1) =15a(2) =35a(3) =120a(4) =143a(5) =323a(6) =728a(7) =899a(8) =1520a(9) =1763a(10) =3599a(11) =5183a(12) =10403a(13) =11663a(14) =19043a(15) =22499a(16) =32399a(17) =36863a(18) =39203a(19) =51983a(20) =57599a(21) =72899a(22) =76728a(23) =79523a(24) =97343a(25) =116280a(26) =121103a(27) =176399a(28) =186623a(29) =188355