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 A280725 #16 Feb 11 2025 14:23:04 %S A280725 3,1,3,0,9,2,6,4,4,2,0,1,2,2,7,3,0,8,9,7,6,3,4,3,8,7,0,9,5,6,0,1,3,2, %T A280725 7,1,3,4,0,3,1,2,9,9,4,4,7,7,1,6,5,5,2,2,5,1,9,7,8,2,1,3,0,4,2,9,8,1, %U A280725 2,0,7,7,1,2,1,9,2,2,1,4,8,5,8,3,9,2,1,4,7,1,6,7,2,0,7,9,7,6,1,7,0,3,6,3,3 %N A280725 Decimal expansion of 22*sin(Pi/22). %C A280725 The ratio of the perimeter of a regular 11-gon (hendecagon) to its diameter (largest diagonal). %C A280725 Also least positive root of x^5 - 11x^4 - 484x^3 + 3993x^2 + 43923x - 161051. %H A280725 <a href="/index/Al#algebraic_05">Index entries for algebraic numbers, degree 5</a>. %e A280725 3.130926442012273089763438709560132713403129944771655225197821304298120771... %p A280725 evalf(22*sin(Pi/22),100); # _Wesley Ivan Hurt_, Feb 01 2017 %t A280725 RealDigits[22*Sin[Pi/22], 10, 120][[1]] (* _Amiram Eldar_, Jun 26 2023 *) %o A280725 (PARI) 22*sin(Pi/22) %Y A280725 Cf. For other n-gons: A010466 (n=4), 10*A019827 (n=5, 10), A280533 (n=7), A280585 (n=8), A280633 (n=9), A280819 (n=12). %K A280725 nonn,cons %O A280725 1,1 %A A280725 _Rick L. Shepherd_, Jan 07 2017