Sums of two powers of 7.

Terms

a(0) =2a(1) =8a(2) =14a(3) =50a(4) =56a(5) =98a(6) =344a(7) =350a(8) =392a(9) =686a(10) =2402a(11) =2408a(12) =2450a(13) =2744a(14) =4802a(15) =16808a(16) =16814a(17) =16856a(18) =17150a(19) =19208a(20) =33614a(21) =117650a(22) =117656a(23) =117698a(24) =117992a(25) =120050a(26) =134456a(27) =235298a(28) =823544a(29) =823550