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Search: id:A166387
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| A166387 |
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a(n) = sum (floor (j^2/n), 1 <= j <= n-1) - floor ((n-1)(n-2)/3), n >= 2. |
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+0
1
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| 0, 1, 1, 0, 1, 1, 2, 2, 0, 1, 3, 0, 1, 3, 4, 0, 2, 1, 3, 2, 1, 3, 6, 2, 0, 3, 3, 0, 3, 3, 6, 2, 0, 3, 7, 0, 1, 5, 6, 0, 2, 1, 5, 4, 3, 5, 10, 4, 2, 3, 3, 0, 3, 5, 8, 2, 0, 3, 9, 0, 3, 7, 10, 0, 2, 1, 5, 4, 3, 7, 12, 0, 0, 7, 5, 2, 5, 5, 12, 6, 0, 3, 9, 0, 1, 7, 8, 0, 4, 3, 7, 4, 5, 9, 16, 0, 4
(list; graph; listen)
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OFFSET
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2,7
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COMMENT
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a(n) = 0 when n = 2, any prime of the form 4k+1 with k >= 1 and any
product of these without repetition, e.g. 2x5x17.
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CROSSREFS
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a(n) = A166373 - A128422(2:)
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KEYWORD
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nonn,new
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AUTHOR
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Christopher Hunt Gribble (chris.eveswell(AT)virgin.net), Oct 13 2009
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EXTENSIONS
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Corrected and enhanced by Christopher Hunt Gribble (chris.eveswell(AT)virgin.net), Dec 01 2009
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