Numbers k such that sopfr(k + sopfr(k)) = sopfr(k) + sopfr(sopfr(k)), where sopfr = A001414.

Terms

a(0) =1a(1) =2a(2) =56a(3) =98a(4) =102a(5) =198a(6) =402a(7) =611a(8) =780a(9) =981a(10) =1230a(11) =1275a(12) =1377a(13) =2288a(14) =3685a(15) =4030a(16) =6600a(17) =8851a(18) =9282a(19) =11371a(20) =11607a(21) =13680a(22) =15390a(23) =15862a(24) =16445a(25) =20916a(26) =21266a(27) =21867a(28) =22606a(29) =27504