Numbers k such that k + sigma(k) + sigma(sigma(k)) is a square.

Terms

a(0) =2a(1) =9a(2) =19a(3) =98a(4) =141a(5) =176a(6) =319a(7) =396a(8) =467a(9) =691a(10) =729a(11) =970a(12) =1113a(13) =1279a(14) =1447a(15) =1473a(16) =1873a(17) =1974a(18) =2403a(19) =3712a(20) =5208a(21) =5965a(22) =6777a(23) =7183a(24) =8353a(25) =8769a(26) =8881a(27) =8962a(28) =10137a(29) =10180