Numbers k that divide sigma(k^2) where sigma is the sum of divisors function (A000203).

Terms

a(0) =1a(1) =39a(2) =793a(3) =2379a(4) =7137a(5) =13167a(6) =76921a(7) =78507a(8) =230763a(9) =238887a(10) =549549a(11) =692289a(12) =863577a(13) =1491633a(14) =1672209a(15) =2076867a(16) =4317885a(17) =7615179a(18) =8329831a(19) =10441431a(20) =23402223a(21) =24989493a(22) =37776123a(23) =53306253a(24) =53695813a(25) =55871145a(26) =74968479a(27) =83766969a(28) =133854435a(29) =144688401