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 A221532 #21 Jan 14 2021 21:16:14 %S A221532 10,45,150,756,1530,5100,7301,38646,42940,430263,391149 %N A221532 The number of n-digit numbers whose last k digits are divisible by k for k = 1..n. %e A221532 There are ten one-digit numbers divisible by 1 so a(1)=10. %e A221532 For two-digit numbers, the ones digit must be such that the two-digit number is divisible by 2 which gives 45 numbers, that is, all even numbers from 10 to 98 to satisfy the requirement. So a(2)=45. %Y A221532 Cf. A164836. %K A221532 nonn,base %O A221532 1,1 %A A221532 _Shyam Sunder Gupta_, Aug 07 2013