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 A115545 #6 Jul 15 2021 09:14:03 %S A115545 122449,489796,122448979591836734693877551020408163265306122449, %T A115545 489795918367346938775510204081632653061224489796 %N A115545 Numbers k such that the concatenation of 6*k with k gives a square. %e A115545 734694_122449 = 857143^2. %Y A115545 Cf. A102567, A106497, A115527 - A115556. %K A115545 nonn,base %O A115545 1,1 %A A115545 _Giovanni Resta_, Jan 25 2006