Sums of 3 distinct powers of 7.

Terms

a(0) =57a(1) =351a(2) =393a(3) =399a(4) =2409a(5) =2451a(6) =2457a(7) =2745a(8) =2751a(9) =2793a(10) =16815a(11) =16857a(12) =16863a(13) =17151a(14) =17157a(15) =17199a(16) =19209a(17) =19215a(18) =19257a(19) =19551a(20) =117657a(21) =117699a(22) =117705a(23) =117993a(24) =117999a(25) =118041a(26) =120051a(27) =120057a(28) =120099a(29) =120393