Numbers n such that determinant[{{n, sigma(n)}, {n+1, sigma(n+1)}}] is a perfect square.

Terms

a(0) =1a(1) =15a(2) =62a(3) =1061a(4) =16049a(5) =163863a(6) =288099a(7) =1416729a(8) =2083059a(9) =13348207a(10) =30204871a(11) =35154349a(12) =59852792a(13) =63224809a(14) =283280355a(15) =464690354a(16) =484273317a(17) =546188411a(18) =950441582a(19) =1282519339a(20) =1395158907a(21) =1406767949a(22) =1438132761a(23) =2530805413a(24) =3442427162a(25) =4774940354a(26) =9019693953