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 A262653 #6 Oct 31 2015 15:03:18 %S A262653 4,141,11411,5114115,551141155,1455114115541,1111455114115541111, %T A262653 55111145511411554111155,1021551111455114115541111551201, %U A262653 12102155111145511411554111155120121,531210215511114551141155411115512012135,101531210215511114551141155411115512012135101 %N A262653 Minimal nested palindromic base-6 primes with seed 4; see Comments. %C A262653 Using only base-6 digits 0,1,2,3,4,5, 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 base-6 primes with seed s. %H A262653 Clark Kimberling, <a href="/A262653/b262653.txt">Table of n, a(n) for n = 1..300</a> %e A262653 a(3) = 11411 is the least base-6 prime having a(2) = 141 in its middle. Triangular format: %e A262653 4 %e A262653 141 %e A262653 11411 %e A262653 5114115 %e A262653 551141155 %e A262653 1455114115541 %t A262653 s = {4}; base = 6; z = 20; Do[NestWhile[# + 1 &, 1, ! PrimeQ[tmp = FromDigits[Join[#, IntegerDigits[Last[s]], Reverse[#]] &[IntegerDigits[#, base]], base]] &]; %t A262653 AppendTo[s, FromDigits[IntegerDigits[tmp, base]]], {z}]; s (* A262653 *) %t A262653 Map[FromDigits[ToString[#], base] &, s] (* A262654 *) %t A262653 (* _Peter J. C. Moses_, Sep 01 2015 *) %Y A262653 Cf. A261881 (base 10), A262654, A262627. %K A262653 nonn,easy,base %O A262653 1,1 %A A262653 _Clark Kimberling_, Oct 27 2015