Numbers n such that sigma(n) - n = sigma(n') - n', where n' is the arithmetic derivative of n.

Terms

a(0) =1a(1) =4a(2) =27a(3) =369a(4) =2120a(5) =2853a(6) =3125a(7) =6620a(8) =24932a(9) =65588a(10) =210404a(11) =245444a(12) =347049a(13) =823543a(14) =833444a(15) =968204a(16) =1610684a(17) =3125492a(18) =5046044a(19) =5856308a(20) =9339020a(21) =9900236a(22) =10614092a(23) =10636772a(24) =11421164a(25) =11617772a(26) =13276892a(27) =16116764a(28) =16244156a(29) =18422444