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 A230854 #13 Aug 17 2019 12:59:13
%S A230854 4,8,10,12,14,18,20,22,24,30,36,38,40,42,46,48,50,52,58,64,66,68,70,
%T A230854 74,76,78,80,82,88,90,92,94,96,100,102,104,106,112,118,120,122,124,
%U A230854 128,130,132,134,140,146,148,150,152,156,158,160,162,164,170,172,174,176,178,182,184,186,188
%N A230854 Numbers n such that m + (sum of digits in base-3 representation of m) = n has exactly two solutions.
%H A230854 Donovan Johnson, <a href="/A230854/b230854.txt">Table of n, a(n) for n = 1..10000</a>
%H A230854 <a href="/index/Coi#Colombian">Index entries for Colombian or self numbers and related sequences</a>
%t A230854 Select[Tally[Table[m+Total[IntegerDigits[m,3]],{m,200}]],#[[2]]==2&][[All,1]] (* _Harvey P. Dale_, Aug 17 2019 *)
%Y A230854 Related base-3 sequences: A053735, A134451, A230641, A230642, A230643, A230853, A230854, A230855, A230856, A230639, A230640, A010063 (trajectory of 1)
%K A230854 nonn,base
%O A230854 1,1
%A A230854 _N. J. A. Sloane_, Oct 31 2013