Numbers having three 7's in base 10.

Terms

a(0) =777a(1) =1777a(2) =2777a(3) =3777a(4) =4777a(5) =5777a(6) =6777a(7) =7077a(8) =7177a(9) =7277a(10) =7377a(11) =7477a(12) =7577a(13) =7677a(14) =7707a(15) =7717a(16) =7727a(17) =7737a(18) =7747a(19) =7757a(20) =7767a(21) =7770a(22) =7771a(23) =7772a(24) =7773a(25) =7774a(26) =7775a(27) =7776a(28) =7778a(29) =7779