Numbers k such that phi(k) | sigma(k + 1).

Terms

a(0) =1a(1) =2a(2) =4a(3) =5a(4) =6a(5) =9a(6) =10a(7) =13a(8) =14a(9) =20a(10) =21a(11) =30a(12) =32a(13) =34a(14) =43a(15) =45a(16) =54a(17) =55a(18) =65a(19) =68a(20) =70a(21) =104a(22) =109a(23) =114a(24) =129a(25) =132a(26) =140a(27) =151a(28) =153a(29) =160