a(n)=(s(n)+1)/8, where s(n)=n-th base 8 palindrome that starts with 7.

Terms

a(0) =1a(1) =8a(2) =57a(3) =58a(4) =59a(5) =60a(6) =61a(7) =62a(8) =63a(9) =64a(10) =449a(11) =458a(12) =467a(13) =476a(14) =485a(15) =494a(16) =503a(17) =512a(18) =3585a(19) =3593a(20) =3601a(21) =3609a(22) =3617a(23) =3625a(24) =3633a(25) =3641a(26) =3650a(27) =3658a(28) =3666a(29) =3674