a(n)=(s(n)+5)/8, where s(n)=n-th base 8 palindrome that starts with 3.

Terms

a(0) =1a(1) =4a(2) =25a(3) =26a(4) =27a(5) =28a(6) =29a(7) =30a(8) =31a(9) =32a(10) =193a(11) =202a(12) =211a(13) =220a(14) =229a(15) =238a(16) =247a(17) =256a(18) =1537a(19) =1545a(20) =1553a(21) =1561a(22) =1569a(23) =1577a(24) =1585a(25) =1593a(26) =1602a(27) =1610a(28) =1618a(29) =1626