Numbers n such that sigma(lambda(n)) = lambda(sigma(n)).

Terms

a(0) =1a(1) =9a(2) =18a(3) =36a(4) =63a(5) =72a(6) =126a(7) =252a(8) =504a(9) =712a(10) =729a(11) =1458a(12) =1716a(13) =2136a(14) =2916a(15) =2982a(16) =3484a(17) =3588a(18) =4402a(19) =5103a(20) =5467a(21) =5832a(22) =7120a(23) =7332a(24) =8800a(25) =9798a(26) =9894a(27) =10206a(28) =10452a(29) =11928