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 A381152 #12 Feb 15 2025 16:49:09 %S A381152 8,6,4,8,0,6,2,6,5,9,7,7,2,0,9,9,6,7,2,3,1,1,8,2,0,6,5,8,5,8,6,2,3,3, %T A381152 3,7,0,3,8,2,8,5,5,5,6,9,0,2,2,8,3,9,9,6,2,1,3,2,0,9,5,7,3,9,8,9,3,3, %U A381152 2,7,0,9,3,4,1,1,8,7,1,2,9,6,4,8,0,4,0,2,3,3 %N A381152 Decimal expansion of the isoperimetric quotient of a regular pentagon. %C A381152 The isoperimetric quotient of a closed curve is equal to 4*Pi*A/p^2, where A is the area enclosed by the curve and p is its perimeter. For a regular n-gon, this is equivalent to Pi/(n*tan(Pi/n)). %C A381152 The isoperimetric quotient of a circle is 1. %H A381152 Paolo Xausa, <a href="/A381152/b381152.txt">Table of n, a(n) for n = 0..10000</a> %H A381152 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/IsoperimetricQuotient.html">Isoperimetric Quotient</a>. %H A381152 Wikipedia, <a href="https://en.wikipedia.org/wiki/Isoperimetric_inequality">Isoperimetric inequality</a>. %F A381152 Equals Pi/(5*tan(Pi/5)) = (Pi/5)*A019952. %F A381152 Equals (4/25)*Pi*A102771. %e A381152 0.86480626597720996723118206585862333703828555690228... %t A381152 First[RealDigits[Pi/(5*Tan[Pi/5]), 10, 100]] %Y A381152 Cf. A019952, A102771. %Y A381152 Cf. isoperimetric quotient of other regular polygons: A073010 (triangle), A003881 (square), A093766 (hexagon), A381153 (heptagon), A196522 (octagon), A381154 (9-gon), A381155 (10-gon), A381156 (11-gon), A381157 (12-gon). %K A381152 nonn,cons,easy %O A381152 0,1 %A A381152 _Paolo Xausa_, Feb 15 2025