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 A381154 #7 Feb 15 2025 16:49:32 %S A381154 9,5,9,0,5,0,5,4,1,8,7,3,6,0,9,3,5,8,0,7,4,5,4,3,3,0,6,7,0,8,6,4,3,4, %T A381154 1,3,0,2,0,1,8,1,5,8,0,9,7,5,2,8,5,8,7,3,4,3,7,2,0,7,8,9,2,8,0,3,9,1, %U A381154 9,4,5,1,0,3,7,5,6,4,9,7,6,1,4,4,0,5,7,7,1,2 %N A381154 Decimal expansion of the isoperimetric quotient of a regular 9-gon. %C A381154 For the definition of isoperimetric quotient, see A381152. %H A381154 Paolo Xausa, <a href="/A381154/b381154.txt">Table of n, a(n) for n = 0..10000</a> %H A381154 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/IsoperimetricQuotient.html">Isoperimetric Quotient</a>. %H A381154 Wikipedia, <a href="https://en.wikipedia.org/wiki/Isoperimetric_inequality">Isoperimetric inequality</a>. %F A381154 Equals Pi/(9*tan(Pi/9)) = Pi/(9*A019918). %F A381154 Equals (4/81)*Pi*A256853. %e A381154 0.959050541873609358074543306708643413020181580975... %t A381154 First[RealDigits[Pi/(9*Tan[Pi/9]), 10, 100]] %Y A381154 Cf. A019918, A256853. %Y A381154 Cf. isoperimetric quotient of other regular polygons: A073010 (triangle), A003881 (square), A381152 (pentagon), A093766 (hexagon), A381153 (heptagon), A196522 (octagon), A381155 (10-gon), A381156 (11-gon), A381157 (12-gon). %K A381154 nonn,cons,easy %O A381154 0,1 %A A381154 _Paolo Xausa_, Feb 15 2025