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 A280533 #15 Feb 11 2025 14:21:20 %S A280533 3,1,1,5,2,9,3,0,7,5,3,8,8,4,0,1,6,6,0,0,4,4,6,3,5,9,0,2,9,5,5,1,2,6, %T A280533 6,3,2,5,2,8,9,7,7,9,6,2,7,0,3,6,2,9,3,7,4,3,6,7,8,1,8,2,2,2,5,6,3,8, %U A280533 9,7,2,4,8,3,9,9,6,6,2,4,6,7,0,4,4,1,3,4,7,3,6,5,1,3,0,2,1,3,8,8,8,8,2,4,5 %N A280533 Decimal expansion of 14*sin(Pi/14). %C A280533 Decimal expansion of the ratio of the perimeter of a regular 7-gon (heptagon) to its diameter (largest diagonal). %H A280533 G. C. Greubel, <a href="/A280533/b280533.txt">Table of n, a(n) for n = 1..10000</a> %H A280533 <a href="/index/Al#algebraic_03">Index entries for algebraic numbers, degree 3</a>. %F A280533 Equals 14*A232736. %e A280533 3.115293075388401660044635902955126632528977962703629374367818222563897248... %t A280533 RealDigits[14*Sin[Pi/14], 10, 129][[1]] (* _G. C. Greubel_, Sep 20 2022 *) %o A280533 (PARI) 14*sin(Pi/14) %o A280533 (SageMath) numerical_approx(14*sin(pi/14), digits=127) # _G. C. Greubel_, Sep 20 2022 %Y A280533 Cf. For other n-gons: A010466 (n=4), 10*A019827 (n=5, 10), A280585 (n=8), A280633 (n=9), A280725 (n=11), A280819 (n=12). %Y A280533 Cf. A232736. %K A280533 nonn,cons %O A280533 1,1 %A A280533 _Rick L. Shepherd_, Jan 04 2017