A004733 Denominator of n!!/(n+3)!!.

3, 8, 15, 16, 105, 128, 315, 256, 3465, 1024, 9009, 2048, 45045, 32768, 109395, 65536, 2078505, 262144, 4849845, 524288, 22309287, 4194304, 50702925, 8388608, 456326325, 33554432, 1017958725, 67108864

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• frac

References

• S. Janson, On the traveling fly problem, Graph Theory Notes of New York, Vol. XXXI, 17, 1996.

Links

• S. Janson, On the traveling fly problem.

Crossrefs

Cf. A004732.

Cf. A001801.

Programs

PARI

a(n) = denominator(prod(i=0, floor((n-1)/2), n-2*i)/prod(i=0, floor((n+2)/2), n+3-2*i)) \\ Michel Marcus, May 24 2013