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 A116307 #7 Jul 17 2021 01:44:02 %S A116307 83,77394229,89158935,36623663376237623663376337, %T A116307 37633762366336633762366237,62366237633663366237633763, %U A116307 63376336623762376336623663,86194223018927804587702130 %N A116307 Numbers k such that k*(k+1) gives the concatenation of two numbers m and m+3. %e A116307 89158935 * 89158936 = 79493157//79493160, where // denotes concatenation. %Y A116307 Cf. A116099, A116301, A116308, A116314. %K A116307 nonn,base %O A116307 1,1 %A A116307 _Giovanni Resta_, Feb 06 2006