7th power analog of Keith numbers.

Terms

a(0) =1a(1) =18a(2) =27a(3) =31a(4) =34a(5) =43a(6) =53a(7) =58a(8) =68a(9) =145a(10) =187a(11) =314a(12) =826a(13) =2975a(14) =37164a(15) =40853a(16) =58530a(17) =72795a(18) =77058a(19) =160703a(20) =187617a(21) =1926759a(22) =6291322a(23) =6628695a(24) =25285305a(25) =31292514a(26) =33968486a(27) =54954185a(28) =71593237a(29) =125921697