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 A115532 #10 Jul 15 2021 06:29:11 %S A115532 2857142857142857142857142857142858, %T A115532 4285714285714285714285714285714287, %U A115532 5714285714285714285714285714285716,19354838709677419354838709677419354838709677419354838709678 %N A115532 Numbers k such that k^2 is the concatenation of two numbers m and 3*m. %Y A115532 Cf. A102567, A106497, A115527 - A115556. %K A115532 nonn,base %O A115532 1,1 %A A115532 _Giovanni Resta_, Jan 25 2006