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 A240523 #23 Feb 16 2025 08:33:21
%S A240523 1,1,2,3,5,8,12,19,29,45,69,105,161,247,377,577,881,1347,2058,3144,
%T A240523 4805,7341,11216,17137,26183,40005,61122,93387,142682,218000,333074,
%U A240523 508892,777518,1187942,1815014,2773095,4236913
%N A240523 a(n) = floor(4^n/((1+sqrt(5))/2)^(2*n)).
%C A240523 a(n) is the perimeter (rounded down) of pentaflake after n iterations, let a(0) = 1. The total number of sides is 5*A000302(n).
%H A240523 G. C. Greubel, <a href="/A240523/b240523.txt">Table of n, a(n) for n = 0..1000</a>
%H A240523 Kival Ngaokrajang, <a href="/A240523/a240523.pdf">Illustration for n = 0..4</a>
%H A240523 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Pentaflake.html">Pentaflake</a>
%H A240523 Wikipedia, <a href="http://en.wikipedia.org/wiki/N-flake">n-flake</a>
%F A240523 Equals floor((2/(phi))^(2*n)), where phi is the golden ratio. - _G. C. Greubel_, Jul 05 2017
%p A240523 A240523:=n->floor(4^n/((1+sqrt(5))/2)^(2*n)); seq(A240523(n), n=0..50); # _Wesley Ivan Hurt_, Apr 07 2014
%t A240523 Table[Floor[4^n/(((1 + Sqrt[5]))/2)^(2 n)], {n, 0, 50}] (* _Wesley Ivan Hurt_, Apr 07 2014 *)
%t A240523 Table[Floor[4^n/GoldenRatio^(2n)],{n,0,40}] (* _Harvey P. Dale_, Mar 24 2018 *)
%o A240523 (PARI) a(n) = floor(4^n/((1+sqrt(5))/2)^(2*n))
%Y A240523 Cf. A000302, A000400, A113212.
%K A240523 nonn,easy
%O A240523 0,3
%A A240523 _Kival Ngaokrajang_, Apr 07 2014