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 A116269 #9 Jul 18 2021 02:51:41 %S A116269 87,3675,6319,8785,48742,51252,87616,3762553,6237441,9217099, %T A116269 3266298273,3520463763,6479536231,6733701721,8063694647,8317860137, %U A116269 4689524709430934473,5310475290569065521,7416797436703661746 %N A116269 Numbers k such that k*(k+7) gives the concatenation of two numbers m and m-3. %Y A116269 Cf. A116205, A116263, A116268, A116270, A116283. %K A116269 nonn,base %O A116269 1,1 %A A116269 _Giovanni Resta_, Feb 06 2006