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Multiplied by 10, this is the real and the imaginary part of sqrt(25i). - Alonso del Arte, Jan 11 2013
Radius of the midsphere (tangent to the edges) in a regular tetrahedron with unit edges. - Stanislav Sykora, Nov 20 2013
Ivan Panchenko, Table of n, a(n) for n = 0..1000
Wikipedia, Platonic solid
A010503 divided by 2.
1/sqrt(8) = 0.353553390593273762200422181052424519642417968844237018294...
Digits:=100; evalf(1/sqrt(8)); # Wesley Ivan Hurt, Mar 27 2014
RealDigits[N[1/Sqrt, 200]] (* Vladimir Joseph Stephan Orlovsky, May 27 2010 *)
(PARI) sqrt(1/8) \\ Charles R Greathouse IV, Apr 25 2016
Cf. Midsphere radii in Platonic solids:
Sequence in context: A096634 A105439 A142972 * A112756 A121795 A253027
Adjacent sequences: A020762 A020763 A020764 * A020766 A020767 A020768
N. J. A. Sloane