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 A116273 #12 Jul 18 2021 02:51:26 %S A116273 90,9078,9900,733673,999000,88225294,99990000,8900869207,9296908811, %T A116273 9604060396,9999900000,326666333266,673333666733,700730927007, %U A116273 972603739726,999999000000,34519562953736,39737862788837 %N A116273 Numbers k such that k*(k+2) gives the concatenation of two numbers m and m-2. %e A116273 90 is a member since 90*92 = 8280 = 82 80. %e A116273 9078 is a member since 9078*9080 = 82428240 = 8242 8240. %Y A116273 Cf. A054214, A116266, A116272, A116274, A116279. %K A116273 nonn,base %O A116273 1,1 %A A116273 _Giovanni Resta_, Feb 06 2006