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 A214426 #9 Aug 18 2012 01:49:04
%S A214426 8,121,373,786435
%N A214426 Numbers n palindromic in exactly four bases b, 2 <= b <= 10.
%C A214426 Searched up to 10^18. Rick Regan mentions these four numbers, also found by Bill Beckmann, at the end of his webpage. - _T. D. Noe_, Aug 18 2012
%H A214426 Rick Regan, <a href="http://www.exploringbinary.com/finding-numbers-that-are-palindromic-in-multiple-bases/">Finding numbers that are palindromic in multiple bases</a>
%F A214426 A050812(n) = 4.
%e A214426 8 is palindromic in bases 3, 7, 9, and 10.
%e A214426 121 is palindromic in bases 3, 7, 8, and 10.
%e A214426 373 is palindromic in bases 4, 7, 9, and 10.
%e A214426 786435 is palindromic in bases 2, 4, 7, and 8.
%t A214426 n = -1; t = {}; While[Length[t] < 4, n++; If[Count[Table[s = IntegerDigits[n, m]; s == Reverse[s], {m, 2, 10}], True] == 4, AppendTo[t, n]]]; t
%Y A214426 Cf. A050813, A214423, A214424, A214425 (palindromic in 0-3 bases).
%K A214426 nonn,base,hard
%O A214426 1,1
%A A214426 _T. D. Noe_, Jul 18 2012