Numbers k such that phi(sigma(k)) = k.

Terms

a(0) =1a(1) =2a(2) =8a(3) =12a(4) =128a(5) =240a(6) =720a(7) =6912a(8) =32768a(9) =142560a(10) =712800a(11) =1140480a(12) =1190400a(13) =3345408a(14) =3571200a(15) =5702400a(16) =14859936a(17) =29719872a(18) =50319360a(19) =118879488a(20) =2147483648a(21) =3889036800a(22) =4389396480a(23) =21946982400a(24) =47416320000a(25) =92177326080a(26) =133145026560a(27) =331914240000a(28) =460886630400a(29) =665725132800