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 A104957 Decimal expansion of the area of the regular 7-gon (heptagon) of circumradius = 1. 4

%I

%S 2,7,3,6,4,1,0,1,8,8,6,3,8,1,0,4,3,3,0,4,7,9,5,5,5,8,4,3,3,5,9,2,0,2,

%T 1,2,5,8,1,3,1,7,0,8,1,5,4,8,0,4,0,6,3,5,1,4,3,2,2,2,2,3,5,3,1,5,7,8,

%U 2,1,0,6,0,7,1,8,7,7,7,5,4,5,9,5,3,0,3,8,0,2,4,1,1,8,4,6,8,4,3,7,8,1,2,9,1

%N Decimal expansion of the area of the regular 7-gon (heptagon) of circumradius = 1.

%C Equivalently, the area in the complex plane of the smallest convex set containing all order-7 roots of unity.

%H Eric Weisstein et al., <a href="http://mathworld.wolfram.com/RootofUnity.html">"Root of Unity."</a>

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

%F Root[ -823543 + 537824*#1^2 - 87808*#1^4 + 4096*#1^6 &, 5, 0] = 3*Sin[(2*Pi)/7] - Sin[(12*Pi)/7]/2

%e 2.736410188638104330479555843359202125813170815480406351432222353...

%t Floor[n/2]*Sin[(2*Pi)/n] - Sin[(4*Pi*Floor[n/2])/n]/2 /. n -> 7

%Y Cf. A104954, A104955, A104956.

%K nonn,cons

%O 1,1

%A Joseph Biberstine (jrbibers(AT)indiana.edu), Mar 30 2005

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Last modified March 29 14:37 EDT 2020. Contains 333107 sequences. (Running on oeis4.)