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A129294
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Number of divisors of n^3 - 1 that are not greater than n.
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5
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1, 2, 2, 3, 2, 4, 2, 5, 3, 5, 2, 7, 2, 4, 7, 5, 3, 6, 2, 6, 6, 6, 2, 13, 4, 4, 4, 8, 4, 10, 3, 6, 5, 6, 5, 14, 2, 6, 5, 8, 3, 10, 3, 8, 10, 5, 3, 16, 3, 9, 5, 9, 2, 11, 5, 8, 7, 4, 3, 20, 2, 5, 9, 11, 4, 18, 4, 6, 5, 8, 3, 14, 5, 4, 8, 6, 4, 17, 2, 21, 5, 6, 3, 16, 6, 10, 8, 8, 2, 14, 5, 9, 7, 6, 5, 16
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OFFSET
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2,2
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COMMENTS
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a(n) = #{d: d<=n and A068601(n) mod d = 0};
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LINKS
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EXAMPLE
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a(100) = #{1,3,7,9,11,13,21,27,33,37,39,63,77,91,99} = 15.
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MATHEMATICA
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Table[Count[Divisors[n^3-1], _?(#<n+1&)], {n, 2, 100}] (* Harvey P. Dale, Sep 27 2018 *)
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PROG
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(PARI) a(n) = sumdiv(n^3-1, d, d <= n); \\ Michel Marcus, Aug 01 2018
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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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