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 A116224 #10 Jul 18 2021 06:48:50 %S A116224 23,27,10357253,10577583,45531191,45991881,12823841629508531559818193, %T A116224 17153953024599261169512903,34319291138166088695725681, %U A116224 41203057971387248588060861,75861857890090990570762781 %N A116224 Numbers k such that k concatenated with k+9 gives the product of two numbers which differ by 9. %e A116224 45991881//45991890 = 67817310 * 67817319, where // denotes concatenation. %Y A116224 Cf. A116216, A116223, A116355. %K A116224 nonn,base %O A116224 1,1 %A A116224 _Giovanni Resta_, Feb 06 2006