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A167315
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Totally multiplicative sequence with a(p) = 5*(p-3) for prime p.
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1
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1, -5, 0, 25, 10, 0, 20, -125, 0, -50, 40, 0, 50, -100, 0, 625, 70, 0, 80, 250, 0, -200, 100, 0, 100, -250, 0, 500, 130, 0, 140, -3125, 0, -350, 200, 0, 170, -400, 0, -1250, 190, 0, 200, 1000, 0, -500, 220, 0, 400, -500, 0, 1250, 250, 0, 400, -2500, 0, -650, 280
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OFFSET
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1,2
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LINKS
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FORMULA
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Multiplicative with a(p^e) = (5*(p-3))^e. If n = Product p(k)^e(k) then a(n) = Product (5*(p(k)-3))^e(k).
a(3k) = 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]] - 3)^fi[[All, 2]])); Table[a[n]*5^PrimeOmega[n], {n, 1, 100}] (* G. C. Greubel, Jun 09 2016 *)
f[p_, e_] := (5*(p-3))^e; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Oct 22 2023 *)
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CROSSREFS
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KEYWORD
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sign,easy,mult
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AUTHOR
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STATUS
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approved
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