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A184274
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Number of distinct n X 3 toroidal 0..3 arrays.
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2
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24, 700, 29184, 1398500, 71582944, 3817765120, 209430787824, 11728124734500, 667199944873344, 38430716856090160, 2235968978631715024, 131176846748291651840, 7749524484709164817824, 460543169377106318541400, 27509778650786228522002432
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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T[n_, k_] := (1/(n*k))*Sum[Sum[EulerPhi[c]*EulerPhi[d]*4^(n*k/LCM[c, d]), {d, Divisors[k]}], {c, Divisors[n]}]; a[n_] := T[n, 3]; Array[a, 15] (* Jean-François Alcover, Oct 31 2017, after Andrew Howroyd *)
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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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