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0,1
Equals sum_{n=0..infinity} (-1)^n*binomial(2n,n)/8^n = 1/A115754 . Averaging this constant with sqrt(2) = A002193 = sum_{n=0..inf} binomial(2n,n)/8^n yields A145439.
Height (from a vertex to the opposite face) of regular tetrahedron with unit edge. - Stanislav Sykora, May 31 2012
Jolley, Summation of Series, Dover (1961) eq. (168) on page 32.
Table of n, a(n) for n=0..104.
D. H. Lehmer, Interesting series involving the Central Binomial Coefficient, Am. Math. Monthly 92, no 7 (1985) 449-457.
= 1-(1/2)/2 +(1*3)/(2*4)/2^2 - (1*3*5)/(2*4*6)/2^3+... [Jolley]
0.816496580927726056140063577...
evalf(sqrt(2/3)) ;
RealDigits[N[Sqrt[2/3], 200]][[1]] (* Vladimir Joseph Stephan Orlovsky, Mar 04 2011*)
Sequence in context: A033812 A019717 A007404 * A240982 A182551 A005486
Adjacent sequences: A157694 A157695 A157696 * A157698 A157699 A157700
cons,easy,nonn
R. J. Mathar, Mar 04 2009
approved