a(n)=least k such that base 8 representation of n begins at s(k), where s=A031055.

Terms

a(0) =6a(1) =5a(2) =4a(3) =3a(4) =2a(5) =1a(6) =9a(7) =6a(8) =100a(9) =85a(10) =69a(11) =53a(12) =37a(13) =21a(14) =88a(15) =86a(16) =5a(17) =82a(18) =67a(19) =51a(20) =35a(21) =19a(22) =72a(23) =70a(24) =68a(25) =4a(26) =64a(27) =49a(28) =33a(29) =17