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 A153048 #2 Mar 30 2012 17:26:28
%S A153048 319,337,357,363,371,387,409,447,591,663,681,701,801,827,893
%N A153048 Numbers n with property that n^2 is a concatenation of two 3-digit primes.
%C A153048 There are exactly 15 such numbers.
%e A153048 Corresponding squares are: 101761, 113569, 127449, 131769, 137641, 149769, 167281, 199809, 349281, 439569, 463761, 491401, 641601, 683929, 797449.
%t A153048 c = 0; t = 1000; re = Sort[Reap[Do[If[PrimeQ[p], Do[If[PrimeQ[q], r = p*t + q; s = Sqrt[r]; If[s == Floor[s], c++; Sow[s]]], {q, 101, 999, 2}]], {p, 101, 999, 2}]][[2, 1]]]
%K A153048 fini,full,nonn,base
%O A153048 1,1
%A A153048 _Zak Seidov_, Dec 17 2008