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 A069664 #21 Aug 05 2025 07:49:50
%S A069664 2,11,101,3001,21001,102001,2100001,30000001,200001001,2010000001,
%T A069664 30000000001,110000000101,2000001000001,20000000100001,
%U A069664 200000010000001,1100010000000001,20000001000000001,110000000000000101,2000000000000100001,20000000100000000001
%N A069664 Largest n-digit prime with minimum digit sum.
%H A069664 Joel B. Lewis and T. D. Noe, <a href="/A069664/b069664.txt">Table of n, a(n) for n = 1..100</a>
%t A069664 Table[ Max[ Flatten[Table[ If[PrimeQ[10^n + 1], 10^n + 1, If[PrimeQ[10^n + 10^i + 10^j + 1], 10^n + 10^i + 10^j + 1, 0]], {i, 0, n}, {j, 0, i}]]], {n, 0, 50}] (* Program works so long as there exists an n-digit prime with digit sum 4 or less. *)
%Y A069664 Cf. A007953, A069661, A069662, A069663.
%K A069664 nonn,base
%O A069664 1,1
%A A069664 _Amarnath Murthy_, Apr 05 2002
%E A069664 a(7)-a(12) from _Tom Mueller_, Apr 28 2004
%E A069664 a(13) and onwards added by _Joel B. Lewis_, Jan 07 2008