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A184269
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Number of distinct n X 7 toroidal binary arrays.
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2
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20, 1182, 99880, 9587580, 981706832, 104715443852, 11488774559744, 1286742755471400, 146402730743793240, 16865594582168158776, 1962541914958813595480, 230271584688553159320640, 27207473390887478569212080, 3233802551602631768613571584
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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^(7*n/ilcm(c, d)),
d=divisors(n)), c=[1, 7])/(7*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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