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 A280819 #14 Aug 21 2023 12:16:26 %S A280819 3,1,0,5,8,2,8,5,4,1,2,3,0,2,4,9,1,4,8,1,8,6,7,8,6,0,5,1,4,8,8,5,7,9, %T A280819 9,4,0,1,8,8,8,2,6,8,1,5,8,3,9,1,6,6,1,6,5,7,6,8,0,3,8,4,8,7,7,8,0,6, %U A280819 8,3,6,9,6,9,8,5,6,2,3,9,6,3,0,6,8,4,1,5,6,9,6,3,3,0,9,9,5,9,8,6,2,5,0,7,4 %N A280819 Decimal expansion of 12*sin(Pi/12). %C A280819 The ratio of the perimeter of a regular 12-gon (dodecagon) to its diameter (greatest diagonal). %C A280819 A quartic integer: the least positive root of x^4 - 144x^2 + 1296. %H A280819 <a href="/index/Al#algebraic_04">Index entries for algebraic numbers, degree 4</a> %F A280819 12*A019824. %e A280819 3.105828541230249148186786051488579940188826815839166165768038487780683696... %t A280819 First@ RealDigits@ N[12 Sin[Pi/12], 120] (* _Michael De Vlieger_, Feb 05 2017 *) %o A280819 (PARI) 12*sin(Pi/12) %o A280819 (PARI) polrootsreal(x^4-144*x^2+1296)[3] \\ _Charles R Greathouse IV_, Feb 05 2017 %Y A280819 Cf. For other n-gons: A010466 (n=4), 10*A019827 (n=5, 10), A280533 (n=7), A280585 (n=8), A280633 (n=9), A280725 (n=11). %K A280819 nonn,cons %O A280819 1,1 %A A280819 _Rick L. Shepherd_, Jan 08 2017