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A218447
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a(n) = Sum_{k>=0} floor(n/(5*k + 4)).
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3
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0, 0, 0, 0, 1, 1, 1, 1, 2, 3, 3, 3, 4, 4, 5, 5, 6, 6, 7, 8, 9, 9, 9, 9, 11, 11, 11, 12, 14, 15, 15, 15, 16, 16, 17, 17, 19, 19, 20, 21, 22, 22, 23, 23, 25, 26, 26, 26, 28, 29, 29, 29, 30, 30, 32, 32, 34, 35, 36, 37, 38, 38, 38, 39, 41, 41, 41, 41, 43, 44, 45, 45, 48, 48, 49, 49, 51, 51, 52, 53, 54
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OFFSET
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0,9
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COMMENTS
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LINKS
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MAPLE
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g:= n -> nops(select(t -> t mod 5 = 4, numtheory:-divisors(n))):
g(0):= 0:
ListTools:-PartialSums(map(g, [$0..100])); # Robert Israel, Apr 29 2021
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PROG
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(PARI) a(n)=sum(k=0, n, (n\(5*k+4)))
(Maxima) A218447[n]:=sum(floor(n/(5*k+4)), k, 0, n)$
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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