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 A220490 #19 Jan 14 2021 21:15:59 %S A220490 9,98,996,9996,99960,999960,9999780,99999360,999999360,9999999360, %T A220490 99999951480 %N A220490 The largest n-digit number whose last k digits are divisible by k for k = 1..n. %e A220490 There are ten one-digit numbers divisible by 1 and the largest is 9 so a(1)=9. %e A220490 For two-digit numbers, the ones digit must make it divisible by 2, which gives 98 as the largest to satisfy the requirement. So a(2)=98. %Y A220490 Cf. A164836. %K A220490 nonn,base %O A220490 1,1 %A A220490 _Shyam Sunder Gupta_, Aug 07 2013