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A309407
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a(n) = round(sqrt(3*n + 9/4)), with a(0) = 1.
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5
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1, 2, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 16, 16, 16
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OFFSET
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0,2
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COMMENTS
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For the first 1750 terms, A046693(n)-a(n) is either 0 or 1.
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LINKS
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FORMULA
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a(n) = round(sqrt(3*n + 9/4)).
a(12*k^2 - 6*k) = 6*k - 2 for k>0.
a(12*k^2 + 6*k) = 6*k + 2 for k>0. (End)
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MATHEMATICA
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Table[If[n == 0, 1, Round[Sqrt[3 n + 9/4]]], {n, 0, 88}]
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PROG
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(PARI) a(n) = if (n, round(sqrt(3*n + 9/4)), 1); \\ Michel Marcus, Jan 18 2022
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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