Numbers whose base-7 representation contains exactly four 4's.

Terms

a(0) =1600a(1) =4001a(2) =6402a(3) =8803a(4) =9832a(5) =10175a(6) =10518a(7) =10861a(8) =11008a(9) =11057a(10) =11106a(11) =11155a(12) =11176a(13) =11183a(14) =11190a(15) =11197a(16) =11200a(17) =11201a(18) =11202a(19) =11203a(20) =11205a(21) =11206a(22) =11211a(23) =11218a(24) =11253a(25) =11302a(26) =11547a(27) =11890a(28) =13605a(29) =16006