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 A116258 #9 Jul 18 2021 02:52:57 %S A116258 8444,8809,69125298546226023970,69855225553525294043, %T A116258 74604750601020544518,75334677608319814591,92496418993920707745, %U A116258 93226346001219977818,97975871048715228293,98705798056014498366 %N A116258 Numbers k such that k*(k+9) gives the concatenation of two numbers m and m-5. %e A116258 8809 * 8818 = 7767//7762, where // denotes concatenation. %Y A116258 Cf. A116180, A116245, A116257, A116264. %K A116258 nonn,base %O A116258 1,1 %A A116258 _Giovanni Resta_, Feb 06 2006