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 A293288 #20 Nov 16 2017 01:49:06
%S A293288 0,0,32,332,2908,23900,192844,1547068,12388068,99135316,793162780,
%T A293288 6345516140,50764701756,406119132924,3248957101772,25991667561644,
%U A293288 207933369171996,1663467029827132,13307736442512524,106461892083564380,851695138117736668,6813561108806027412
%N A293288 Number of level n squares on a Sierpinski carpet that are enclosed in a circle with the same center and diameter.
%C A293288 There are 8^n level n squares on a Sierpinski carpet.
%C A293288 The terms of this sequence have a common factor 4.
%C A293288 Lim_{n->infinity} a(n)/a(n-1) = 8.
%C A293288 Lim_{n->infinity} a(n)/8^n = 0.73872777586247800994....
%H A293288 Yi Yang, <a href="/A293288/b293288.txt">Table of n, a(n) for n = 0..32</a>
%H A293288 Chyanog, <a href="/A293288/a293288.png">Illustration of initial terms</a> (the red squares are counted)
%H A293288 Wayne, Ickiverar, <a href="http://bbs.emath.ac.cn/thread-9655-4-1.html">The C++ code generating the sequence</a>
%Y A293288 Cf. A001018, A261849, A293289.
%K A293288 nonn
%O A293288 0,3
%A A293288 _Yi Yang_, Oct 04 2017