Numbers beginning with letter 'f' in English.

Terms

a(0) =4a(1) =5a(2) =14a(3) =15a(4) =40a(5) =41a(6) =42a(7) =43a(8) =44a(9) =45a(10) =46a(11) =47a(12) =48a(13) =49a(14) =50a(15) =51a(16) =52a(17) =53a(18) =54a(19) =55a(20) =56a(21) =57a(22) =58a(23) =59a(24) =400a(25) =401a(26) =402a(27) =403a(28) =404a(29) =405