Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 4500 articles have referenced us, often saying "we would not have discovered this result without the OEIS".
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 *)
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