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A167296
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Totally multiplicative sequence with a(p) = 4*(p-2) for prime p.
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1
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1, 0, 4, 0, 12, 0, 20, 0, 16, 0, 36, 0, 44, 0, 48, 0, 60, 0, 68, 0, 80, 0, 84, 0, 144, 0, 64, 0, 108, 0, 116, 0, 144, 0, 240, 0, 140, 0, 176, 0, 156, 0, 164, 0, 192, 0, 180, 0, 400, 0, 240, 0, 204, 0, 432, 0, 272, 0, 228, 0, 236, 0, 320, 0, 528, 0, 260, 0, 336
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OFFSET
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1,3
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LINKS
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FORMULA
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Multiplicative with a(p^e) = (4*(p-2))^e. If n = Product p(k)^e(k) then a(n) = Product (4*(p(k)-2))^e(k).
a(2k) = 0 for k >= 1.
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MATHEMATICA
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a[1] = 1; a[n_] := (fi = FactorInteger[n]; Times @@ ((fi[[All, 1]] - 2)^fi[[All, 2]])); Table[a[n]*4^PrimeOmega[n], {n, 1, 100}] (* G. C. Greubel, Jun 06 2016 *)
f[p_, e_] := (4*(p-2))^e; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Oct 18 2023 *)
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CROSSREFS
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KEYWORD
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nonn,easy,mult
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AUTHOR
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STATUS
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approved
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