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 A179552 #17 Jul 23 2025 16:49:22 %S A179552 3,0,1,5,0,2,8,3,2,3,9,5,8,2,4,5,7,0,6,8,3,7,1,5,5,6,9,5,3,0,4,6,9,8, %T A179552 4,3,1,4,3,3,5,9,0,9,8,3,1,7,1,4,6,9,0,5,1,7,7,9,5,4,0,5,1,8,9,2,1,0, %U A179552 5,0,3,8,5,6,8,2,4,1,8,7,0,8,0,8,9,3,3,9,3,3,6,8,2,4,4,9,2,6,1,4,5,7,0,6,2 %N A179552 Decimal expansion of the volume of pentagonal pyramid with edge length 1. %C A179552 Pentagonal pyramid: 6 faces, 6 vertices, and 10 edges. %C A179552 Also equals the covariance-matrix eigenvalue of the regular icosahedron with unit edge lengths. - _Chittaranjan Pardeshi_, Jul 18 2025 %H A179552 Wikipedia, <a href="https://en.wikipedia.org/wiki/Covariance_matrix">Covariance matrix</a>. %H A179552 Wikipedia, <a href="https://en.wikipedia.org/wiki/Regular_icosahedron">Regular icosahedron</a>. %H A179552 Wolfram Alpha, <a href="http://www.wolframalpha.com/input/?i=Johnson+solid+2">Johnson solid 2</a> %H A179552 <a href="/index/Al#algebraic_02">Index entries for algebraic numbers, degree 2</a> %F A179552 Equals (5+sqrt(5))/24. %e A179552 0.3015028323958245706837155695304698431433590983171469051779540518921... %t A179552 RealDigits[N[(5+Sqrt[5])/24,200]] %o A179552 (PARI) (5+sqrt(5))/24 \\ _Charles R Greathouse IV_, Oct 30 2023 %Y A179552 Cf. A001622, A010527, A102208, A179290, A179292, A179294, A179449, A179450, A179451, A179452. %K A179552 nonn,cons,easy %O A179552 0,1 %A A179552 _Vladimir Joseph Stephan Orlovsky_, Jul 19 2010