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 A261822 #8 Sep 29 2015 12:31:19
%S A261822 5,151,31513,3315133,11331513311,191133151331191,9919113315133119199,
%T A261822 39991911331513311919993,353999191133151331191999353,
%U A261822 13539991911331513311919993531,741353999191133151331191999353147
%N A261822 Minimal nested palindromic primes with seed 5.
%C A261822 Let s be a palindrome and put a(1) = s. Let a(2) be the least palindromic prime having s in the middle; for n > 2, let a(n) be the least palindromic prime have a(n-1) in the middle. Then (a(n)) is the sequence of minimal nested palindromic primes with seed s.
%H A261822 Clark Kimberling, <a href="/A261822/b261822.txt">Table of n, a(n) for n = 1..200</a>
%e A261822 As a triangle:
%e A261822 .......5
%e A261822 ......151
%e A261822 .....31513
%e A261822 ....3315133
%e A261822 ..11331513311
%e A261822 191133151331191
%t A261822 s = {5}; Do[NestWhile[# + 1 &, 1, ! PrimeQ[tmp = FromDigits[Join[#, IntegerDigits[Last[s]], Reverse[#]] &[IntegerDigits[#]]]] &]; AppendTo[s, tmp], {15}]; s
%t A261822 (* _Peter J. C. Moses_, Sep 01 2015 *)
%Y A261822 Cf. A261881 (seed 0, with guide to related sequences).
%K A261822 nonn,easy,base
%O A261822 1,1
%A A261822 _Clark Kimberling_, Sep 23 2015