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%I M2700 #27 Nov 03 2017 22:13:05
%S 1,1,3,7,35,155,1395,11811,200787,3309747,109221651,3548836819,
%T 230674393235,14877590196755,1919209135381395,246614610741341843,
%U 63379954960524853651,16256896431763117598611,8339787869494479328087443,4274137206973266943778085267
%N Gaussian binomial coefficient [ n, n/2 ] for q=2.
%D J. Goldman and G.-C. Rota, The number of subspaces of a vector space, pp. 75-83 of W. T. Tutte, editor, Recent Progress in Combinatorics. Academic Press, NY, 1969.
%D I. P. Goulden and D. M. Jackson, Combinatorial Enumeration. Wiley, NY, 1983, p. 99.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%D M. Sved, Gaussians and binomials, Ars. Combinatoria, 17A (1984), 325-351.
%H T. D. Noe, <a href="/A006099/b006099.txt">Table of n, a(n) for n=0..50</a>.
%H M. Sved, <a href="/A006095/a006095.pdf">Gaussians and binomials</a>, Ars. Combinatoria, 17A (1984), 325-351. (Annotated scanned copy)
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/q-BinomialCoefficient.html">q-Binomial Coefficient</a>.
%F a(n) ~ c * 2^(n^2/4), where c = 1 / QPochhammer[1/2, 1/2] = A065446 = 3.46274661945506361153795734292443116454... if n is even, and c = 2^(-1/4) / QPochhammer[1/2, 1/2] = 2^(-1/4) * A065446 = 2.911811219231681420726836976930855961516... if n is odd. - _Vaclav Kotesovec_, Jun 22 2014
%t Table[QBinomial[n,Floor[n/2],2],{n,0,20}] (* _Harvey P. Dale_, Sep 07 2013 *)
%Y Cf. A065446.
%K nonn
%O 0,3
%A _N. J. A. Sloane_
%E More terms from _Harvey P. Dale_, Sep 07 2013
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