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 A384478 #13 May 31 2025 11:05:38 %S A384478 1,9,0,5,7,6,1,7,9,8,8,5,5,6,5,5,3,2,2,8,5,2,8,8,8,5,2,4,2,1,4,6,9,4, %T A384478 8,4,7,5,1,1,0,4,5,3,5,6,9,4,8,6,5,3,1,0,3,3,9,1,0,2,4,3,9,9,2,6,1,9, %U A384478 7,6,1,4,2,8,4,2,1,6,5,0,8,8,1,5,4,1,6,1,8,0,6,1,1,4,1,4,7,6,4,6 %N A384478 Decimal expansion of the largest interior angle (in radians) in Albrecht Dürer's approximate construction of the regular pentagon. %D A384478 Alfred S. Posamentier and Herbert A. Hauptman, 101 great ideas for introducing key concepts in mathematics: a resource for secondary school teachers, Corwin Press, Inc., 2001. See pages 144-145. %H A384478 Stefano Spezia, <a href="/A384474/a384474.png">Albrecht Dürer's approximate construction of the regular pentagon</a>. %H A384478 Wikipedia, <a href="https://en.wikipedia.org/wiki/Albrecht_Dürer">Albrecht Dürer</a>. %F A384478 Equals 3*Pi - 2*(A384474 + A384476). %F A384478 Equals ((Pi + 4*arccsc(2/sqrt(2 - sqrt(2*(5 - 2*sqrt(3) + sqrt(-187 + 108*sqrt(3))))))))/2. %e A384478 1.9057617988556553228528885242146948475110453569... %t A384478 RealDigits[((Pi + 4 ArcCsc[2/Sqrt[2 - Sqrt[2 (5 - 2 Sqrt[3] + Sqrt[-187 + 108 Sqrt[3]])]]]))/2,10,100][[1]] %Y A384478 Cf. A228719, A384477 (in degrees). %Y A384478 Cf. A384473, A384474, A384475, A384476. %K A384478 nonn,cons %O A384478 1,2 %A A384478 _Stefano Spezia_, May 30 2025