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 A384477 #17 May 31 2025 11:05:34 %S A384477 1,0,9,1,9,2,1,0,7,8,3,1,6,8,8,7,6,7,0,7,3,5,5,4,1,5,7,3,1,6,5,9,8,8, %T A384477 0,0,6,4,8,9,4,4,7,7,0,1,1,2,8,4,7,5,8,7,0,7,5,4,7,1,4,8,2,0,1,3,5,4, %U A384477 1,4,5,8,6,6,4,4,4,4,5,6,6,4,7,1,7,8,7,3,2,7,1,2,3,2,6,3,4,6,5,6 %N A384477 Decimal expansion of the largest interior angle (in degrees) in Albrecht Dürer's approximate construction of the regular pentagon. %D A384477 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 A384477 Stefano Spezia, <a href="/A384473/a384473.png">Albrecht Dürer's approximate construction of the regular pentagon</a>. %H A384477 Wikipedia, <a href="https://en.wikipedia.org/wiki/Albrecht_Dürer">Albrecht Dürer</a>. %F A384477 Equals 540 - 2*(A384473 + A384475). %F A384477 Equals (90*(Pi + 4*arccsc(2/sqrt(2 - sqrt(2*(5 - 2*sqrt(3) + sqrt(-187 + 108*sqrt(3))))))))/Pi. %e A384477 109.19210783168876707355415731659880064894477011... %t A384477 RealDigits[(90 (Pi + 4 ArcCsc[2/Sqrt[2 - Sqrt[2 (5 - 2 Sqrt[3] + Sqrt[-187 + 108 Sqrt[3]])]]]))/Pi,10,100][[1]] %Y A384477 Cf. A228719, A384478 (in radians). %Y A384477 Cf. A384473, A384474, A384475, A384476. %K A384477 nonn,cons %O A384477 3,3 %A A384477 _Stefano Spezia_, May 30 2025