A374957 - OEIS

%I #12 Aug 07 2024 03:01:33

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

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

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

%N Decimal expansion of the circumradius of a regular heptagon with unit side length.

%H Paolo Xausa, <a href="/A374957/b374957.txt">Table of n, a(n) for n = 1..10000</a>

%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RegularPolygon.html">Regular Polygon</a>.

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Regular_polygon">Regular polygon</a>.

%F Equals csc(Pi/7)/2 = A121598/2.

%F Equals 1/(2*sin(Pi/7)) = 1/A272487.

%F Equals A374971/cos(Pi/7) = A374971/A073052.

%F Equals A374972 + A374971.

%e 1.15238243548124325262057511177342755672225094380...

%t First[RealDigits[Csc[Pi/7]/2, 10, 100]]

%Y Cf. A374971 (apothem), A374972 (sagitta), A178817 (area).

%Y Cf. circumradius of other polygons with unit side length: A020760 (triangle), A010503 (square), A300074 (pentagon), A285871 (octagon), A375151 (9-gon), A001622 (10-gon), A375190 (11-gon), A188887 (12-gon).

%Y Cf. A073052, A121598, A272487.

%K nonn,cons,easy

%O 1,3

%A _Paolo Xausa_, Jul 26 2024