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Search: id:A112580
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| A112580 |
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Number of 3-D arrays of nonnegative integers with plane sums 2. |
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+0
3
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| 1, 12, 1152, 431424, 427723200, 920031955200, 3777894212198400, 27039993414897254400, 315084437077115278540800, 5667616936309704095784960000, 150796432741520745587273564160000
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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P. J. Cameron and T. W. Mueller, Decomposable functors and the exponential principle, II, in preparation
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FORMULA
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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)
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EXAMPLE
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a(2)=12: eight 0-1 arrays and four with 2s at opposite vertices
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CROSSREFS
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Cf. A001499 (2-D case), A112578, A112579.
Sequence in context: A109229 A112457 A091782 this_sequence A103269 A033564 A054351
Adjacent sequences: A112577 A112578 A112579 this_sequence A112581 A112582 A112583
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KEYWORD
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nonn,easy
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AUTHOR
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Peter J. Cameron (p.j.cameron(AT)qmul.ac.uk), Sep 14 2005
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