|
|
A112580
|
|
Number of 3-D arrays of nonnegative integers with plane sums 2.
|
|
2
|
|
|
1, 12, 1152, 431424, 427723200, 920031955200, 3777894212198400, 27039993414897254400, 315084437077115278540800, 5667616936309704095784960000, 150796432741520745587273564160000
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
REFERENCES
|
P. J. Cameron and T. W. Mueller, Decomposable functors and the exponential principle, II, in preparation
|
|
LINKS
|
|
|
FORMULA
|
a(n) = b(n) + Sum (k/n)*(n choose k)^3*b(k)*a(n-k), where b(n) counts indecomposable arrays (A112578 with first term 1).
|
|
EXAMPLE
|
a(2)=12: eight 0-1 arrays and four with 2s at opposite vertices.
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|