A374971 - OEIS

%I #18 Feb 05 2025 10:02:42

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

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

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

%N Decimal expansion of the apothem (inradius) of a regular heptagon with unit side length.

%H Paolo Xausa, <a href="/A374971/b374971.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/Apothem">Apothem</a>.

%H <a href="/index/Al#algebraic_06">Index entries for algebraic numbers, degree 6</a>.

%F Equals cot(Pi/7)/2 = A178818/2.

%F Equals 1/(2*tan(Pi/7)) = 1/(2*A343058).

%F Equals A374957*cos(Pi/7) = A374957*A073052.

%F Equals A374957 - A374972.

%e 1.0382606982861682835817694307429201653528601033...

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

%o (PARI) .5/(Pi/7) \\ _Charles R Greathouse IV_, Feb 05 2025

%Y Cf. A374957 (circumradius), A374972 (sagitta), A178817 (area).

%Y Cf. apothem of other polygons with unit side length: A020769 (triangle), A020761 (square), A375067 (pentagon), A010527 (hexagon), A174968 (octagon), A375152 (9-gon), A179452 (10-gon), A375191 (11-gon), A375193 (12-gon).

%Y Cf. A178818, A073052, A343058.

%K nonn,cons,easy,changed

%O 1,3

%A _Paolo Xausa_, Jul 26 2024