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 A302139 #52 Jul 14 2025 13:53:57
%S A302139 8,12,16,20,24,32,64,120,128,256,512,600,1024,2048,4096,8192,16384,
%T A302139 32768,65536,131072,262144,524288,1048576,2097152,4194304,8388608,
%U A302139 16777216,33554432,67108864,134217728,268435456,536870912,1073741824,2147483648,4294967296,8589934592,17179869184,34359738368,68719476736
%N A302139 Numbers k such that A111336(k) = 4.
%C A302139 All terms beyond a(12) = 600 are powers of 2.
%H A302139 Harvey P. Dale, <a href="/A302139/b302139.txt">Table of n, a(n) for n = 1..1000</a>
%H A302139 Wikipedia, <a href="http://en.wikipedia.org/wiki/List_of_regular_polytopes">Regular Polytopes</a>.
%H A302139 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (2).
%F A302139 a(n) = 2^(n-3) for n >= 13.
%e A302139 For k >= 3, 2^k is a term because the four regular polytopes with 2^k faces are the 2^k-gon, the k-dimensional orthoplex, the 2^(k-1)-dimensional cube and the (2^k-1)-dimensional simplex. [Corrected by _Jianing Song_, Dec 09 2018]
%t A302139 LinearRecurrence[{2},{8,12,16,20,24,32,64,120,128,256,512,600,1024},50] (* _Harvey P. Dale_, Jul 14 2025 *)
%Y A302139 Cf. A111336.
%K A302139 easy,nonn
%O A302139 1,1
%A A302139 _Jianing Song_, Apr 02 2018