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 A374957 #16 Aug 29 2025 13:38:08 %S A374957 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 A374957 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 A374957 2,6,6,7,1,3,8,9,2,3,9,7,9,8,1,8,9,5,5,5,7,1 %N A374957 Decimal expansion of the circumradius of a regular heptagon with unit side length. %H A374957 Paolo Xausa, <a href="/A374957/b374957.txt">Table of n, a(n) for n = 1..10000</a> %H A374957 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RegularPolygon.html">Regular Polygon</a>. %H A374957 Wikipedia, <a href="https://en.wikipedia.org/wiki/Regular_polygon">Regular polygon</a>. %H A374957 <a href="/index/Al#algebraic_06">Index entries for algebraic numbers, degree 6</a>. %F A374957 Equals csc(Pi/7)/2 = A121598/2. %F A374957 Equals 1/(2*sin(Pi/7)) = 1/A272487. %F A374957 Equals A374971/cos(Pi/7) = A374971/A073052. %F A374957 Largest of the 6 real-valued roots of 7*x^6-14*x^4+7*x^2-1=0. - _R. J. Mathar_, Aug 29 2025 %e A374957 1.15238243548124325262057511177342755672225094380... %t A374957 First[RealDigits[Csc[Pi/7]/2, 10, 100]] %o A374957 (PARI) .5/sin(Pi/7) \\ _Charles R Greathouse IV_, Feb 05 2025 %Y A374957 Cf. A374971 (apothem), A374972 (sagitta), A178817 (area). %Y A374957 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 A374957 Cf. A073052, A121598, A272487. %K A374957 nonn,cons,easy,changed %O A374957 1,3 %A A374957 _Paolo Xausa_, Jul 26 2024