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 A053378 #5 Jun 13 2020 15:14:27 %S A053378 8,88,888,5888,85888,885888,8885888,58885888,558885888,8558885888, %T A053378 58558885888,858558885888,5858558885888,85858558885888, %U A053378 585858558885888,5585858558885888,55585858558885888,855585858558885888 %N A053378 a(n) contains n digits (either '5' or '8') and is divisible by 2^n. %H A053378 Ray Chandler, <a href="/A053378/b053378.txt">Table of n, a(n) for n = 1..1000</a> %F A053378 a(n)=a(n-1)+10^(n-1)*(8-3*[a(n-1)/2^(n-1) mod 2]) i.e. a(n) ends with a(n-1); if (n-1)-th term is divisible by 2^n then n-th term begins with an 8, if not then n-th term begins with a 5. %Y A053378 Cf. A023413, A050621, A050622, A035014. %K A053378 base,nonn %O A053378 1,1 %A A053378 _Henry Bottomley_, Mar 06 2000