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 A262641 #10 Oct 25 2015 17:58:52 %S A262641 1,111,41114,1411141,20141114102,12120141114102121, %T A262641 24012120141114102121042,142401212014111410212104241, %U A262641 41424012120141114102121042414,314142401212014111410212104241413,4131414240121201411141021210424141314,30413141424012120141114102121042414131403 %N A262641 Minimal nested palindromic base-5 primes with seed 1; see Comments. %C A262641 Using only base-5 digits 0,1,2,3,4, 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-5 primes with seed s. %H A262641 Clark Kimberling, <a href="/A262641/b262641.txt">Table of n, a(n) for n = 1..300</a> %e A262641 a(3) = 41114 is the least base-5 prime having a(2) = 111 in its middle. %e A262641 Triangular format: %e A262641 1 %e A262641 111 %e A262641 41114 %e A262641 1411141 %e A262641 20141114102 %e A262641 12120141114102121 %e A262641 24012120141114102121042 %t A262641 s = {1}; base = 5; z = 20; Do[NestWhile[# + 1 &, 1, ! PrimeQ[tmp = FromDigits[Join[#, IntegerDigits[Last[s]], Reverse[#]] &[IntegerDigits[#, base]], base]] &]; %t A262641 AppendTo[s, FromDigits[IntegerDigits[tmp, base]]], {z}]; s (* A262641 *) %t A262641 Map[FromDigits[ToString[#], base] &, s] (* A262642 *) %t A262641 (* _Peter J. C. Moses_, Sep 01 2015 *) %Y A262641 Cf. A261881 (base 10), A262627, A262642. %K A262641 nonn,easy,base %O A262641 1,2 %A A262641 _Clark Kimberling_, Oct 24 2015