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%I #12 Jul 30 2015 22:12:31
%S 2,2,4,4,16,16,32,32,256,256,512,512,2048,2048,4096,4096,65536,65536,
%T 131072,131072,524288,524288,1048576,1048576,8388608,8388608,16777216,
%U 16777216,67108864,67108864,134217728,134217728,4294967296,4294967296
%N Denominator of mean deviation of a symmetrical binomial distribution on n elements.
%C Also denominator of x(n)=Sum(x(k)*x(n-k-1):0<=k<n), x(0)=1/2: x(n)=A098597(n)/a(n+2). - _Reinhard Zumkeller_, Feb 06 2008
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/BinomialDistribution.html">Binomial Distribution</a>
%H <a href="/index/Di#divseq">Index to divisibility sequences</a>
%F a(1)=2, a(n) = a(n-1)*A006519(n). - _Jon Perry_, Mar 31 2004
%t Denominator[Table[If[OddQ[n], n!!/2/(n-1)!!, (n-1)!!/2/(n-2)!! ], {n, 50}]]
%Y Cf. A086116.
%Y Twice A101926.
%K nonn,frac
%O 1,1
%A _Eric W. Weisstein_, Jul 10 2003
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