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 A260250 #10 Oct 02 2015 13:05:44
%S A260250 1300000000031,713000000000317,1471300000000031741,
%T A260250 12147130000000003174121,3121471300000000031741213,
%U A260250 1213121471300000000031741213121,33121312147130000000003174121312133,323312131214713000000000317412131213323
%N A260250 Minimal nested palindromic primes with seed 000000000.
%C A260250 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 having a(n-1) in the middle. Then (a(n)) is the sequence of minimal nested palindromic primes with seed s. (For A260250, the seed is not an integer, so that the offset is 2.)
%H A260250 Clark Kimberling, <a href="/A260250/b260250.txt">Table of n, a(n) for n = 2..200</a>
%e A260250 As a triangle:
%e A260250 000000000
%e A260250 1300000000031
%e A260250 713000000000317
%e A260250 1471300000000031741
%e A260250 12147130000000003174121,
%e A260250 3121471300000000031741213
%e A260250 1213121471300000000031741213121,
%t A260250 s0 = "000000000"; s = {ToExpression[s0]};Do[NestWhile[# + 1 &, 1, ! PrimeQ[tmp = FromDigits[Join[#, IntegerDigits[Last[s], 10, Max[StringLength[s0],Length[IntegerDigits[Last[s]]]]], Reverse[#]]&[IntegerDigits[#]]]] &]; AppendTo[s, tmp], {10}]; s0 <> ", " <> StringTake[ToString[Rest[s]], {2, -2}]
%t A260250 (* _Peter J. C. Moses_, Sep 23 2015 *)
%Y A260250 Cf. A261881.
%K A260250 nonn,base,easy
%O A260250 2,1
%A A260250 _Clark Kimberling_, Sep 24 2015