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A184266
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Number of distinct n X 4 toroidal binary arrays.
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2
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6, 40, 352, 4156, 52488, 699600, 9587580, 134223976, 1908881900, 27487869472, 399822505524, 5864063067176, 86607686432616, 1286742765058960, 19215358428046176, 288230376353050696, 4340410370537249376, 65588423376053309360, 994182417449857925988
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OFFSET
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1,1
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LINKS
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FORMULA
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MAPLE
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with(numtheory):
a:= n-> add(add(phi(c)*phi(d) *2^(4*n/ilcm(c, d)),
d=divisors(n)), c=[1, 2, 4])/(4*n):
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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