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 A115440 #5 Jun 18 2021 18:16:51 %S A115440 7747,8021,33294318,66705683,98000201,340465755425,476452552745, %T A115440 523547447256,659534244576,866013200681,998000002001,3695104677080134, %U A115440 3755782995538768,4198081170077531,4803478892324966,5196521107675035 %N A115440 Numbers whose square is the concatenation of two numbers k and k+8. %e A115440 6001_6009 = 7747^2. %Y A115440 Cf. A030467, A106497, A115429, A115427, A115438, A115439, A115441, A115442, A115443, A115444, A115445, A115446, A115447. %K A115440 base,nonn %O A115440 1,1 %A A115440 _Giovanni Resta_, Jan 24 2006