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A359236
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Number of divisors of 5*n-2 of form 5*k+1.
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10
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1, 1, 1, 2, 1, 1, 2, 1, 1, 3, 1, 1, 2, 1, 1, 3, 1, 2, 2, 1, 1, 3, 1, 1, 2, 2, 1, 3, 2, 1, 2, 1, 1, 4, 1, 1, 2, 1, 1, 4, 1, 3, 2, 1, 1, 3, 1, 1, 2, 2, 2, 3, 1, 1, 3, 1, 1, 5, 1, 1, 2, 2, 1, 3, 1, 2, 2, 2, 1, 3, 1, 1, 3, 3, 1, 4, 1, 1, 2, 1, 2, 4, 1, 2, 2, 1, 1, 3, 1, 3
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OFFSET
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1,4
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COMMENTS
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Also number of divisors of 5*n-2 of form 5*k+3.
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LINKS
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FORMULA
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G.f.: Sum_{k>0} x^k/(1 - x^(5*k-2)).
G.f.: Sum_{k>0} x^(3*k-2)/(1 - x^(5*k-4)).
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MATHEMATICA
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a[n_] := DivisorSum[5*n-2, 1 &, Mod[#, 5] == 1 &]; Array[a, 100] (* Amiram Eldar, Aug 23 2023 *)
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PROG
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(PARI) a(n) = sumdiv(5*n-2, d, d%5==1);
(PARI) a(n) = sumdiv(5*n-2, d, d%5==3);
(PARI) my(N=100, x='x+O('x^N)); Vec(sum(k=1, N, x^k/(1-x^(5*k-2))))
(PARI) my(N=100, x='x+O('x^N)); Vec(sum(k=1, N, x^(3*k-2)/(1-x^(5*k-4))))
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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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