Numbers which have only digits 5 and 6 in base 10.

Terms

a(0) =5a(1) =6a(2) =55a(3) =56a(4) =65a(5) =66a(6) =555a(7) =556a(8) =565a(9) =566a(10) =655a(11) =656a(12) =665a(13) =666a(14) =5555a(15) =5556a(16) =5565a(17) =5566a(18) =5655a(19) =5656a(20) =5665a(21) =5666a(22) =6555a(23) =6556a(24) =6565a(25) =6566a(26) =6655a(27) =6656a(28) =6665a(29) =6666