a(n)=least k such that base 3 representation of n begins at s(k), where s=A030341.

Terms

a(0) =1a(1) =2a(2) =8a(3) =4a(4) =1a(5) =2a(6) =7a(7) =12a(8) =41a(9) =18a(10) =8a(11) =17a(12) =4a(13) =5a(14) =1a(15) =6a(16) =11a(17) =14a(18) =2a(19) =48a(20) =7a(21) =30a(22) =10a(23) =13a(24) =39a(25) =12a(26) =176a(27) =73a(28) =41a(29) =80