Numbers n such that phi(2n+1) = sigma(n).

Terms

a(0) =6a(1) =7a(2) =27a(3) =38a(4) =55a(5) =85a(6) =87a(7) =127a(8) =188a(9) =236a(10) =255a(11) =266a(12) =445a(13) =451a(14) =655a(15) =717a(16) =913a(17) =1309a(18) =1357a(19) =1490a(20) =1947a(21) =2095a(22) =2515a(23) =2726a(24) =3002a(25) =3247a(26) =3289a(27) =4117a(28) =4237a(29) =5071