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 A020781 #30 Jan 26 2025 14:37:47 %S A020781 2,0,4,1,2,4,1,4,5,2,3,1,9,3,1,5,0,8,1,8,3,1,0,7,0,0,6,2,2,5,4,9,0,9, %T A020781 4,9,3,3,0,4,9,5,6,2,3,3,8,8,0,5,5,8,4,4,0,3,6,0,5,7,7,1,3,9,3,7,5,8, %U A020781 0,0,3,1,4,5,4,7,7,6,2,5,2,2,1,1,6,5,4,9,5,2,7,5,8,7,2,0,0,1,9 %N A020781 Decimal expansion of 1/sqrt(24). %C A020781 Radius of the inscribed sphere (tangent to the faces) for a regular tetrahedron with unit edges. - _Stanislav Sykora_, Nov 20 2013 %D A020781 Jan Gullberg, Mathematics from the Birth of Numbers, W. W. Norton & Co., NY & London, 1997, ยง12.4 Theorems and Formulas (Solid Geometry), p. 450. %H A020781 Ivan Panchenko, <a href="/A020781/b020781.txt">Table of n, a(n) for n = 0..1000</a> %H A020781 Wikipedia, <a href="http://en.wikipedia.org/wiki/Tetrahedron">Tetrahedron</a>. %H A020781 <a href="/index/Al#algebraic_02">Index entries for algebraic numbers, degree 2</a>. %F A020781 Equals A010464/12. - _Stefano Spezia_, Jan 26 2025 %F A020781 Equals 1/A010480 = A020763/2 = 2*A020853 = A187110/3 = A244980/Pi. - _Hugo Pfoertner_, Jan 26 2025 %e A020781 1/sqrt(24) = 0.20412414523193150818310700622549094933... . - _Vladimir Joseph Stephan Orlovsky_, May 30 2010 %t A020781 RealDigits[N[1/Sqrt[24],200]] (* _Vladimir Joseph Stephan Orlovsky_, May 30 2010 *) %Y A020781 Cf. Platonic solids inradii: A020763 (octahedron), A179294 (icosahedron), A237603 (dodecahedron). - _Stanislav Sykora_, Feb 25 2014 %Y A020781 Cf. A010464, A010480, A020763, A020853, A021028, A187110, A244980. %K A020781 nonn,cons,easy %O A020781 0,1 %A A020781 _N. J. A. Sloane_