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 A219542 #15 Aug 11 2015 01:35:52 %S A219542 12,21,37,44,107,108,120,129,191,204,209,210,223,306,315,342,343,345, %T A219542 370,408,413,440,501,642,696,804,955,959,982,995,1002,1044,1063,1065, %U A219542 1070,1080,1107,1169,1200,1275,1281,1290,1301,1306,1315,1349,1385,1503,1910 %N A219542 Numbers n such that n^2 is a concatenation of 3 nonzero squares, leading zeros not allowed. %H A219542 Zak Seidov, <a href="/A219542/b219542.txt">Table of n, a(n) for n = 1..1500</a> %e A219542 a(1) = 12: 12^2 = 144, 1 = 1^2, 4 = 2^2, 4 = 2^2; %e A219542 a(1500) = 3176900^2 = 100, 9, 2693610000, 100 = 10^2, 9 = 3^2, 2693610000 = 51900^2. %Y A219542 Cf. A039686, A048375, A048646, A145848, A147608. %K A219542 nonn,base %O A219542 1,1 %A A219542 _Zak Seidov_, Nov 22 2012