Numbers n such that phi(3n+1) = sigma(n).

Terms

a(0) =3a(1) =21a(2) =23a(3) =27a(4) =30a(5) =65a(6) =69a(7) =95a(8) =133a(9) =143a(10) =203a(11) =253a(12) =264a(13) =413a(14) =447a(15) =537a(16) =618a(17) =667a(18) =672a(19) =715a(20) =863a(21) =897a(22) =1092a(23) =1122a(24) =1221a(25) =1265a(26) =1343a(27) =1824a(28) =2367a(29) =2757