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 A240671 #12 Feb 20 2025 20:17:55
%S A240671 1,1,1,1,2,2,3,4,5,6,8,9,12,15,18,22,28,34,42,52,64,79,98,121,149,183,
%T A240671 226,279,343,423,521,642,791,975,1201,1480,1823,2246,2767,3409,4199,
%U A240671 5173,6373,7851,9672,11915,14679,18083
%N A240671 a(n) = floor(4^n/(2+2*cos(2*Pi/7))^n).
%C A240671 a(n) is the perimeter (rounded down) of a heptaflake after n iterations, let a(0) = 1. The total number of sides is 7*A000302(n). The total number of holes is A023000(n).
%H A240671 Kival Ngaokrajang, <a href="/A240671/a240671.pdf">Illustration of heptaflake for n = 0..3</a>
%H A240671 Wikipedia, <a href="http://en.wikipedia.org/wiki/N-flake">n-flake</a>
%F A240671 a(n) = floor(4^n/A116425(n)^n).
%p A240671 A240671:=n->floor(4^n/(2+2*cos(2*Pi/7))^n); seq(A240671(n), n=0..50); # _Wesley Ivan Hurt_, Apr 10 2014
%t A240671 Table[Floor[4^n/(2 + 2*Cos[2*Pi/7])^n], {n, 0, 50}] (* _Wesley Ivan Hurt_, Apr 10 2014 *)
%o A240671 (PARI) {a(n)=floor(4^n/(2+2*cos(2*Pi/7))^n)}
%o A240671 for (n=0, 100, print1(a(n), ", "))
%Y A240671 Cf. A000302, A023000, A116425, A240523 (pentaflake), A240572 (octaflake).
%K A240671 nonn,easy
%O A240671 0,5
%A A240671 _Kival Ngaokrajang_, Apr 10 2014