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 A374972 #13 Feb 04 2025 10:54:01 %S A374972 1,1,4,1,2,1,7,3,7,1,9,5,0,7,4,9,6,9,0,3,8,8,0,5,6,8,1,0,3,0,5,0,7,3, %T A374972 9,1,3,6,9,3,9,0,8,4,0,4,9,0,1,7,6,3,1,8,9,8,9,8,4,4,4,5,9,8,0,1,9,1, %U A374972 2,4,2,7,8,5,6,9,4,0,9,3,9,4,5,7,3,4,6,9,3,5 %N A374972 Decimal expansion of the sagitta of a regular heptagon with unit side length. %H A374972 Paolo Xausa, <a href="/A374972/b374972.txt">Table of n, a(n) for n = 0..10000</a> %H A374972 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RegularPolygon.html">Regular Polygon</a>. %H A374972 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Sagitta.html">Sagitta</a>. %H A374972 <a href="/index/Al#algebraic_06">Index entries for algebraic numbers, degree 6</a>. %F A374972 Equals tan(Pi/14)/2 = A343059/2. %F A374972 Equals A374957 - A374971. %e A374972 0.114121737195074969038805681030507391369390840490... %t A374972 First[RealDigits[Tan[Pi/14]/2, 10, 100]] %o A374972 (PARI) tan(Pi/14)/2 \\ _Charles R Greathouse IV_, Feb 04 2025 %o A374972 (PARI) polrootsreal(448*x^6-560*x^4+84*x^2-1)[4] \\ _Charles R Greathouse IV_, Feb 04 2025 %Y A374972 Cf. A374957 (circumradius), A374971 (apothem), A178817 (area). %Y A374972 Cf. sagitta of other polygons with unit side length: A020769 (triangle), A174968 (square), A375068 (pentagon), A375069 (hexagon), A374972 (heptagon), A375070 (octagon), A375153 (9-gon), A375189 (10-gon), A375192 (11-gon), A375194 (12-gon). %Y A374972 Cf. A343059. %K A374972 nonn,cons,easy %O A374972 0,3 %A A374972 _Paolo Xausa_, Jul 26 2024