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A079554
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a(n) = floor( d(n) * log(n) / 2 ), where d() = A000005.
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0
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0, 0, 1, 2, 1, 3, 1, 4, 3, 4, 2, 7, 2, 5, 5, 6, 2, 8, 2, 8, 6, 6, 3, 12, 4, 6, 6, 9, 3, 13, 3, 10, 6, 7, 7, 16, 3, 7, 7, 14, 3, 14, 3, 11, 11, 7, 3, 19, 5, 11, 7, 11, 3, 15, 8, 16, 8, 8, 4, 24, 4, 8, 12, 14, 8, 16, 4, 12, 8, 16, 4, 25, 4, 8, 12, 12, 8, 17, 4, 21, 10, 8, 4, 26, 8, 8, 8, 17, 4, 26, 9, 13
(list;
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refs;
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history;
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internal format)
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OFFSET
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1,4
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REFERENCES
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József Sándor, Dragoslav S. Mitrinovic, and Borislav Crstici, Handbook of Number Theory I, Springer Science & Business Media, 2005, Chapter II, p. 41.
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LINKS
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MATHEMATICA
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a[n_] := Floor[DivisorSigma[0, n] * Log[n] / 2]; Array[a, 100] (* Amiram Eldar, Apr 07 2024 *)
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PROG
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(PARI) a(n) = numdiv(n) * log(n) \ 2; \\ Amiram Eldar, Apr 07 2024
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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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