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 A387445 #8 Aug 31 2025 06:36:12 %S A387445 9,9,2,1,1,4,7,0,1,3,1,4,4,7,7,8,3,1,0,4,9,7,9,3,0,4,2,7,8,5,7,7,8,5, %T A387445 2,1,4,5,3,0,3,6,7,0,8,9,6,8,7,9,5,7,3,5,8,7,1,0,2,1,2,2,6,4,1,0,8,8, %U A387445 3,1,1,2,2,5,2,7,1,5,3,4,1,6,1,5,3,6,7,6,6,7,7,5,3,4,5,3,9,8,5,6,4,6,2,2,3,1,6,5,0,4,8,2,8,7,2,8,1,6 %N A387445 Decimal expansion of cos(Pi/25). %H A387445 R. J. Mathar, <a href="https://vixra.org/abs/2210.0026">Reduction formulas of the cosine of integer fractions of pi</a>, (2008) vixra:2210.0026 %H A387445 <a href="/index/Al#algebraic_10">Index entries for algebraic numbers, degree 10</a> %F A387445 Equals sin(23*Pi/50). %F A387445 Largest of the 10 real-valued roots of 1024*x^10 -2560*x^8 +2240*x^6 -32*x^5 -800*x^4 +40*x^3 +100*x^2 -10*x -1 =0. %F A387445 16*this^5 -20*this^3 +5*this = A019863. %e A387445 0.99211470131447783105... %Y A387445 Cf. A019694. %K A387445 nonn,cons,new %O A387445 0,1 %A A387445 _R. J. Mathar_, Aug 29 2025