Numbers n such that phi(n)*sigma(n) = phi(n+1)*sigma(n+1).

Terms

a(0) =5a(1) =55a(2) =56a(3) =123a(4) =135a(5) =147a(6) =175a(7) =304a(8) =351a(9) =644a(10) =1015a(11) =2464a(12) =19304a(13) =61131a(14) =162524a(15) =476671a(16) =567644a(17) =712724a(18) =801944a(19) =2435488a(20) =3346399a(21) =3885056a(22) =4555999a(23) =8085560a(24) =8369360a(25) =12516692a(26) =22702119a(27) =29628800a(28) =83884031a(29) =83994624