This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A261230 #11 Jun 29 2016 00:09:05
%S A261230 -1,0,1,2,3,6,12,28,71,186,494,1317,3478,9045,23265,59856,155779,
%T A261230 412413,1108874,3009228,8188150,22257484,60462422,164715758,452011067,
%U A261230 1253176571
%N A261230 a(n) = A261236(n) - A261237(n).
%F A261230 a(n) = A261236(n) - A261237(n).
%t A261230 Table[Length@ # - 2 First@ FirstPosition[#, k_ /; k != 2] + 1 &@ Map[First@ IntegerDigits[#, 3] &, #] &@ NestWhileList[# - Total@ IntegerDigits[#, 3] &, 3^(n + 1) - 1, # > 3^n - 1 &], {n, 0, 16}] (* _Michael De Vlieger_, Jun 27 2016, Version 10 *)
%o A261230 (Scheme) (define (A261230 n) (- (A261236 n) (A261237 n)))
%Y A261230 Cf. A261234, A261236, A261237.
%K A261230 sign
%O A261230 0,4
%A A261230 _Antti Karttunen_, Aug 16 2015
%E A261230 Terms a(24) & a(25) from _Antti Karttunen_, Jun 27 2016