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 A116242 #9 Jul 18 2021 02:55:02 %S A116242 8871,9008,83352839,99000098,329767122285,670232877710,738226276370, %T A116242 933006600338,999000000998,3779410975143112,3872816717528064, %U A116242 4250291784692547,4278630943941864,4372036686326816,4749511753491299 %N A116242 Numbers k such that k*(k+6) gives the concatenation of two numbers m and m-7. %e A116242 99000098 * 99000104 = 98010199//98010192, where // denotes concatenation. %Y A116242 Cf. A115426, A116237, A116241, A116243, A116256. %K A116242 nonn,base %O A116242 1,1 %A A116242 _Giovanni Resta_, Feb 06 2006