Numbers k such that k + sopfr(k) is a fourth power.

Terms

a(0) =1a(1) =240a(2) =2366a(3) =3681a(4) =6486a(5) =20444a(6) =28428a(7) =50525a(8) =58977a(9) =229986a(10) =234171a(11) =279560a(12) =330840a(13) =390476a(14) =411273a(15) =705966a(16) =809533a(17) =920265a(18) =921214a(19) =1044328a(20) =1202697a(21) =1334469a(22) =1676387a(23) =1676401a(24) =1870204a(25) =1876617a(26) =2084281a(27) =2559900a(28) =3679938a(29) =3745183