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 A020765 #54 Jun 04 2025 00:28:38
%S A020765 3,5,3,5,5,3,3,9,0,5,9,3,2,7,3,7,6,2,2,0,0,4,2,2,1,8,1,0,5,2,4,2,4,5,
%T A020765 1,9,6,4,2,4,1,7,9,6,8,8,4,4,2,3,7,0,1,8,2,9,4,1,6,9,9,3,4,4,9,7,6,8,
%U A020765 3,1,1,9,6,1,5,5,2,6,7,5,9,7,1,2,5,9,6,8,8,3,5,8,1,9,1,0,3,9,3
%N A020765 Decimal expansion of 1/sqrt(8).
%C A020765 Multiplied by 10, this is the real and the imaginary part of sqrt(25i). - _Alonso del Arte_, Jan 11 2013
%C A020765 Radius of the midsphere (tangent to the edges) in a regular tetrahedron with unit edges. - _Stanislav Sykora_, Nov 20 2013
%C A020765 The side of the largest cubical present that can be wrapped (with cutting) by a unit square of wrapping paper. See Problem 10716 link. - _Michel Marcus_, Jul 24 2018
%C A020765 The ratio between the thickness and diameter of a geometrically fair coin having an equal probability, 1/3, of landing on each of its two faces and on its side after being tossed in the air. The calculation is based on comparing the areal projections of the faces and sides of the coin on a circumscribing sphere. (Mosteller, 1965). See A020760 for a physical solution. - _Amiram Eldar_, Sep 01 2020
%D A020765 Frederick Mosteller, Fifty challenging problems of probability, Dover, New York, 1965. See problem 38, pp. 10 and 58-60.
%H A020765 Ivan Panchenko, <a href="/A020765/b020765.txt">Table of n, a(n) for n = 0..1000</a>
%H A020765 Michael L. Catalano-Johnson, Daniel Loeb and John Beebee, <a href="https://www.jstor.org/stable/2695694">A cubical gift: Problem 10716</a>, The American Mathematical Monthly, Vol. 108, No. 1 (Jan., 2001), pp. 81-82.
%H A020765 Wikipedia, <a href="http://en.wikipedia.org/wiki/Tetrahedron">Tetrahedron</a>.
%H A020765 Wikipedia, <a href="http://en.wikipedia.org/wiki/Platonic solid">Platonic solid</a>.
%H A020765 <a href="/index/Al#algebraic_02">Index entries for algebraic numbers, degree 2</a>
%F A020765 A010503 divided by 2.
%F A020765 Equals A201488 minus 1/2. Equals 1/(A010487-4) minus 1/4. - _Jon E. Schoenfield_, Jan 09 2017
%F A020765 Equals Integral_{x=0..oo} x*exp(-x)*BesselJ(0,x) dx. - _Kritsada Moomuang_, Jun 03 2025
%e A020765 1/sqrt(8) = 0.353553390593273762200422181052424519642417968844237018294...
%p A020765 Digits:=100; evalf(1/sqrt(8)); # _Wesley Ivan Hurt_, Mar 27 2014
%t A020765 RealDigits[N[1/Sqrt[8], 200]] (* _Vladimir Joseph Stephan Orlovsky_, May 27 2010 *)
%t A020765 realDigitsRecip[Sqrt[8]] (* The realDigitsRecip program is at A021200 *) (* _Harvey P. Dale_, Apr 05 2025 *)
%o A020765 (PARI) sqrt(1/8) \\ _Charles R Greathouse IV_, Apr 25 2016
%Y A020765 Cf. Midsphere radii in Platonic solids:
%Y A020765 A020761 (octahedron),
%Y A020765 A010503 (cube),
%Y A020765 A019863 (icosahedron),
%Y A020765 A239798 (dodecahedron).
%K A020765 nonn,cons
%O A020765 0,1
%A A020765 _N. J. A. Sloane_