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 A225404 #9 Jun 18 2018 06:40:11
%S A225404 7,8,5,4,3,1,5,9,8,7,8,0,0,5,8,3,2,4,0,6,1,5,6,6,2,9,4,8,1,3,0,3,6,1,
%T A225404 8,4,8,4,6,1,9,2,2,1,3,3,8,6,8,7,8,8,9,0,6,5,9,6,3,5,3,0,2,4,2,3,0,9,
%U A225404 0,5,2,1,6,0,7,0,1,9,9,4,7,5,7,9,3,4,8,6,6,3,3,1,1,4,3,3,6,6,2,4
%N A225404 10-adic integer x such that x^3 == 3 mod 10^n for all n.
%H A225404 Kenny Lau, <a href="/A225404/b225404.txt">Table of n, a(n) for n = 1..10000</a>
%e A225404 7^3 == 3 (mod 10).
%e A225404 87^3 == 3 (mod 100).
%e A225404 587^3 == 3 (mod 1000).
%e A225404 4587^3 == 3 (mod 10000).
%e A225404 34587^3 == 3 (mod 100000).
%e A225404 134587^3 == 3 (mod 1000000).
%o A225404 (PARI) n=0; for(i=1, 100, m=3; for(x=0, 9, if(((n+(x*10^(i-1)))^3)%(10^i)==m, n=n+(x*10^(i-1)); print1(x", "); break)))
%o A225404 (Python) n=7;p=1;i=1;exec("print(i,n//p);i+=1;p*=10;n+=n**3//p*7%10*p;"*10000) # _Kenny Lau_, Jun 07 2018
%K A225404 nonn,base
%O A225404 1,1
%A A225404 _Aswini Vaidyanathan_, May 07 2013