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 A381155 #7 Feb 15 2025 16:49:39 %S A381155 9,6,6,8,8,2,7,9,9,0,4,6,4,0,2,5,4,0,3,2,8,1,8,3,2,1,9,1,8,2,7,5,2,9, %T A381155 8,8,4,6,9,8,6,8,2,4,1,0,8,4,4,0,4,2,9,1,1,0,9,9,3,6,4,1,5,1,8,4,4,7, %U A381155 6,9,2,9,5,1,0,1,3,1,0,2,1,4,3,7,9,2,2,0,5,5 %N A381155 Decimal expansion of the isoperimetric quotient of a regular 10-gon. %C A381155 For the definition of isoperimetric quotient, see A381152. %H A381155 Paolo Xausa, <a href="/A381155/b381155.txt">Table of n, a(n) for n = 0..10000</a> %H A381155 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/IsoperimetricQuotient.html">Isoperimetric Quotient</a>. %H A381155 Wikipedia, <a href="https://en.wikipedia.org/wiki/Isoperimetric_inequality">Isoperimetric inequality</a>. %F A381155 Equals Pi/(10*tan(Pi/10)) = Pi/(10*A019916). %F A381155 Equals (1/25)*Pi*A178816. %e A381155 0.96688279904640254032818321918275298846986824108440... %t A381155 First[RealDigits[Pi/(10*Tan[Pi/10]), 10, 100]] %Y A381155 Cf. A019916, A178816. %Y A381155 Cf. isoperimetric quotient of other regular polygons: A073010 (triangle), A003881 (square), A381152 (pentagon), A093766 (hexagon), A381153 (heptagon), A196522 (octagon), A381154 (9-gon), A381156 (11-gon), A381157 (12-gon). %K A381155 nonn,cons,easy %O A381155 0,1 %A A381155 _Paolo Xausa_, Feb 15 2025