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A359326
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Number of divisors of 6*n-4 of form 6*k+5.
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5
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0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 2, 1, 0, 0, 0, 2, 0, 0, 0, 1, 2, 1, 0, 1, 0, 1, 0, 1, 0, 0, 2, 1, 1, 0, 0, 2, 0, 1, 0, 1, 2, 0, 0, 2, 0, 1, 0, 1, 0, 0, 2, 1, 0, 1, 2, 2, 0, 0, 0, 1, 2, 0, 0, 1, 0, 2, 0, 1, 0, 1, 2, 2, 0, 0, 0, 2, 2, 0, 0, 1, 2, 0
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OFFSET
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1,19
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LINKS
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FORMULA
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G.f.: Sum_{k>0} x^(4*k)/(1 - x^(6*k-1)).
G.f.: Sum_{k>0} x^(5*k-1)/(1 - x^(6*k-2)).
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MATHEMATICA
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a[n_] := DivisorSum[6*n-4, 1 &, Mod[#, 6] == 5 &]; Array[a, 100] (* Amiram Eldar, Aug 14 2023 *)
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PROG
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(PARI) a(n) = sumdiv(6*n-4, d, d%6==5);
(PARI) my(N=100, x='x+O('x^N)); concat([0, 0, 0], Vec(sum(k=1, N, x^(4*k)/(1-x^(6*k-1)))))
(PARI) my(N=100, x='x+O('x^N)); concat([0, 0, 0], Vec(sum(k=1, N, x^(5*k-1)/(1-x^(6*k-2)))))
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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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