A331906 - OEIS

%I #19 May 06 2020 04:58:11

%S 40,1100,7330,25540,65930,136200,263010,458410,740550,1142740,1681640,

%T 2400970,3338850,4495510,5962220,7736150,9924580,12442880,15527670,

%U 19132140,23301600,28070620,33585800,39919140,47157510,55209750,64185300,74311940,85731780,98167130

%N The number of regions inside a pentagram formed by the straight line segments mutually connecting all vertices and all points that divide the sides into n equal parts.

%C The terms are from numeric computation - no formula for a(n) is currently known.

%H Scott R. Shannon, <a href="/A331906/a331906.png">Pentagram regions for n = 1</a>.

%H Scott R. Shannon, <a href="/A331906/a331906_1.png">Pentagram regions for n = 2</a>.

%H Scott R. Shannon, <a href="/A331906/a331906_2.png">Pentagram regions for n = 3</a>.

%H Scott R. Shannon, <a href="/A331906/a331906_3.png">Pentagram regions for n = 4</a>.

%H Scott R. Shannon, <a href="/A331906/a331906_4.png">Pentagram regions for n = 5</a>.

%H Scott R. Shannon, <a href="/A331906/a331906_5.png">Pentagram regions for n = 6</a>.

%H Scott R. Shannon, <a href="/A331906/a331906_6.png">Pentagram regions with random distance-based coloring for n = 1</a>.

%H Scott R. Shannon, <a href="/A331906/a331906_7.png">Pentagram regions with random distance-based coloring for n = 2</a>.

%H Scott R. Shannon, <a href="/A331906/a331906_8.png">Pentagram regions with random distance-based coloring for n = 3</a>.

%H Scott R. Shannon, <a href="/A331906/a331906_9.png">Pentagram regions with random distance-based coloring for n = 4</a>.

%H Scott R. Shannon, <a href="/A331906/a331906_10.png">Pentagram regions with random distance-based coloring for n = 5</a>.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Pentagram.html">Pentagram</a>.

%Y Cf. A331907 (n-gons), A333117 (vertices), A333118 (edges), A007678, A092867, A331452.

%K nonn

%O 1,1

%A _Scott R. Shannon_ and _N. J. A. Sloane_, Jan 31 2020

%E a(7)-a(30) from _Lars Blomberg_, May 06 2020