A112578 Number of indecomposable 3-D arrays of 0's and 1's with plane sums 2.

0, 8, 900, 359424, 370828800, 820150272000, 3435918974208000, 24957654229057536000, 294060698786444083200000, 5334667831784096818790400000, 42889554205720574193041408000000

Offset

1,2

References

P. J. Cameron and T. W. Mueller, Decomposable functors and the exponential principle, II, in preparation

Links

Table of n, a(n) for n=1..11.

P. J. Cameron and T. W. Mueller, Decomposable functors and the exponential principle, II, arXiv:0911.3760 [math.CO]

Formula

a(1)=0, a(n) = (n!)^2*b(n)/2^n for n>1, where b(0)=1 and sum (n-1 choose k-1)*((2n-2k-1)!!)^2*b(k) = ((2n-1)!!)^2.

Example

a(2)=8: six pairs of opposite edges and two inscribed tetrahedra.

Crossrefs

Cf. A010796 (2-D case), A112579, A112580.

Sequence in context: A027725 A265239 A290023 * A112579 A064072 A146536

Adjacent sequences: A112575 A112576 A112577 * A112579 A112580 A112581

Keyword

nonn,easy

Author

Peter J. Cameron, Sep 14 2005

Status

approved