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A168093
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a(n) = number of natural numbers m such that n - 3 <= m <= n + 3.
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0
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3, 4, 5, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
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OFFSET
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0,1
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COMMENTS
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Generalization: If a(n,k) = number of natural numbers m such that n - k <= m <= n + k (k >= 1) then a(n,k) = a(n-1,k) + 1 = n + k for 0 <= n <= k, a(n,k) = a(n-1,k) = 2k + 1 for n >= k + 1 (see, e.g., A158799).
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LINKS
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FORMULA
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a(n) = 3 + n for 0 <= n <= 3, a(n) = 7 for n >= 4.
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MATHEMATICA
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CoefficientList[Series[(3 - 2*x - x^5)/(1 - x)^2, {x, 0, 25}], x] (* G. C. Greubel, Jul 11 2016 *)
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CROSSREFS
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KEYWORD
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nonn,less
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AUTHOR
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STATUS
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approved
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