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 A138027 #7 Jun 08 2025 19:26:47
%S A138027 1357323,1357324,1562041,1562042,1671903,1671904,1889953,1889954,
%T A138027 2010855,2010856,3826141,3826142,3851581,3851582,3933721,3933722,
%U A138027 4652475,4652476,4652501,4738773,4738774,5518809,5518810,5826123
%N A138027 Numbers k where A121561(k) = 4.
%H A138027 Robert G. Wilson v, <a href="/A138027/b138027.txt">Table of n, a(n) for n = 1..100148</a>.
%t A138027 LrgstPrm[n_] := Block[{k = n}, While[ !PrimeQ@k, k-- ]; k]; f[n_] := Block[{c = 0, d = n}, While[d > 1, d = d - LrgstPrm@ d; c++ ]; c]; lst = {}; Do[ If[f@n == 4, AppendTo[lst,n]], {n, 2*10^6}]; lst
%Y A138027 Cf. A121561, A093515, A093513, A138026.
%K A138027 nonn
%O A138027 1,1
%A A138027 _Robert G. Wilson v_, Feb 27 2008, Mar 06 2008