Numbers k such that the multiplicative group of residues prime to k, M_k, is isomorphic to M_{k+1}.

Terms

a(0) =1a(1) =3a(2) =15a(3) =104a(4) =495a(5) =975a(6) =22935a(7) =32864a(8) =57584a(9) =131144a(10) =491535a(11) =2539004a(12) =3988424a(13) =6235215a(14) =7378371a(15) =13258575a(16) =17949434a(17) =25637744a(18) =26879684a(19) =29357475a(20) =32235735a(21) =41246864a(22) =48615735a(23) =184611375a(24) =229944855a(25) =257278724a(26) =290849624a(27) =429461864a(28) =550666515a(29) =671054835