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 A261199 #12 Sep 25 2020 07:14:54
%S A261199 10,101,1013,10133,101333,10133303,1013330309,10133303093,
%T A261199 101333030933,10133303093323,1013330309332339,101333030933233921,
%U A261199 10133303093323392109,101333030933233921097,10133303093323392109703,1013330309332339210970311,10133303093323392109703113
%N A261199 Minimal prime concatenation sequence with base 10 and seed 10.
%H A261199 Clark Kimberling, <a href="/A261199/b261199.txt">Table of n, a(n) for n = 1..500</a>
%e A261199 The least prime starting with seed 10 is 101; the least prime starting with 101 is 1013; the least prime starting with 1013 is 10133. Triangular format:
%e A261199 10
%e A261199 101
%e A261199 1013
%e A261199 10133
%e A261199 101333
%e A261199 10133303
%e A261199 1013330309
%t A261199 b = 10; s = {{10}};
%t A261199 Do[NestWhile[# + 1 &, 0, ! (PrimeQ[FromDigits[tmp = Join[Last[s], (nn = #;
%t A261199 IntegerDigits[nn - Sum[b^n, {n, l = NestWhile[# + 1 &, 1, ! (nn - (Sum[b^n, {n, #}]) < 0) &] - 1}], b, l + 1])], b]]) &]; AppendTo[s, tmp], {20}]; Map[FromDigits, s] (* _Peter J. C. Moses_, Aug 06 2015 *)
%Y A261199 Cf. A261199.
%K A261199 nonn,easy,base
%O A261199 1,1
%A A261199 _Clark Kimberling_, Sep 16 2015