A086117 Denominator of mean deviation of a symmetrical binomial distribution on n elements.

2, 2, 4, 4, 16, 16, 32, 32, 256, 256, 512, 512, 2048, 2048, 4096, 4096, 65536, 65536, 131072, 131072, 524288, 524288, 1048576, 1048576, 8388608, 8388608, 16777216, 16777216, 67108864, 67108864, 134217728, 134217728, 4294967296, 4294967296

Offset: 1

Author

Eric W. Weisstein, Jul 10 2003

Keywords

• nonn
• frac

Comments

Also denominator of x(n)=Sum(x(k)*x(n-k-1):0<=kA098597(n)/a(n+2). - Reinhard Zumkeller, Feb 06 2008

Links

• Eric Weisstein's World of Mathematics, Binomial Distribution
• Index to divisibility sequences

Crossrefs

Cf. A086116, A113474.

Twice A101926.

Programs

Mathematica

Denominator[Table[If[OddQ[n], n!!/2/(n-1)!!, (n-1)!!/2/(n-2)!! ], {n, 50}]]

Formula

a(1)=2, a(n) = a(n-1)*A006519(n). - Jon Perry, Mar 31 2004

a(n) = 2^A113474(n-1). - Alan Michael Gómez Calderón, Apr 03 2025