Numbers k such that sigma(phi(k)) = phi(sigma(k)-k).

Terms

a(0) =2a(1) =18a(2) =50a(3) =1250a(4) =1980a(5) =6900a(6) =61080a(7) =1369020a(8) =2025660a(9) =2820240a(10) =4003230a(11) =4917360a(12) =8597316a(13) =15396360a(14) =15893010a(15) =28725648a(16) =41427360a(17) =53423760a(18) =148663020a(19) =209752500a(20) =212019024a(21) =222746160a(22) =232210080a(23) =281870316a(24) =298848144a(25) =314121180a(26) =322230180a(27) =385612260a(28) =390760260