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 A328706 Dirichlet g.f.: Product_{k>=2} (1 + k^(-s))^2. 10
 1, 2, 2, 3, 2, 6, 2, 6, 3, 6, 2, 12, 2, 6, 6, 9, 2, 12, 2, 12, 6, 6, 2, 24, 3, 6, 6, 12, 2, 22, 2, 14, 6, 6, 6, 28, 2, 6, 6, 24, 2, 22, 2, 12, 12, 6, 2, 42, 3, 12, 6, 12, 2, 24, 6, 24, 6, 6, 2, 52, 2, 6, 12, 22, 6, 22, 2, 12, 6, 22, 2, 60, 2, 6, 12, 12, 6, 22, 2, 42 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Dirichlet convolution of A045778 with itself. LINKS Michael De Vlieger, Table of n, a(n) for n = 1..10000 Jacob Sprittulla, On Colored Factorizations, arXiv:2008.09984 [math.CO], 2020. FORMULA a(n) = Sum_{d|n} A045778(n/d) * A045778(d). MATHEMATICA Block[{f}, f[m_, 1] := 1; f[1, n_] := 0; f[1, 1] := 1; f[0, n_] := 0; f[m_, n_] := f[m, n] = Total[f[# - 1, n/#] & /@ Select[Divisors[n], # <= m &]]; Table[DivisorSum[n, f[n/#, n/#]*f[#, #] &], {n, 80}]] (* Michael De Vlieger, Nov 04 2020 *) CROSSREFS Cf. A045778, A301830. Sequence in context: A107753 A197929 A326849 * A342530 A240090 A078224 Adjacent sequences: A328703 A328704 A328705 * A328707 A328708 A328709 KEYWORD nonn AUTHOR Ilya Gutkovskiy, Oct 26 2019 STATUS approved

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Last modified May 30 03:43 EDT 2023. Contains 363044 sequences. (Running on oeis4.)