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 A166645 Totally multiplicative sequence with a(p) = 5*(p+1) for prime p. 2
 1, 15, 20, 225, 30, 300, 40, 3375, 400, 450, 60, 4500, 70, 600, 600, 50625, 90, 6000, 100, 6750, 800, 900, 120, 67500, 900, 1050, 8000, 9000, 150, 9000, 160, 759375, 1200, 1350, 1200, 90000, 190, 1500, 1400, 101250, 210, 12000, 220, 13500, 12000, 1800 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS G. C. Greubel, Table of n, a(n) for n = 1..10000 FORMULA Multiplicative with a(p^e) = (5*(p+1))^e. If n = Product p(k)^e(k) then a(n) = Product (5*(p(k)+1)^e(k). a(n) = A165826(n) * A003959(n) = 5^bigomega(n) * A003959(n) = 5^A001222(n) * A003959(n). MATHEMATICA a[1] = 1; a[n_] := (fi = FactorInteger[n]; Times @@ ((fi[[All, 1]] + 1)^fi[[All, 2]])); Table[a[n]*5^(PrimeOmega[n]), {n, 1, 100}] (* G. C. Greubel, May 20 2016 *) f[p_, e_] := (5*(p+1))^e; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Oct 17 2023 *) PROG (PARI) a(n) = {my(f = factor(n)); for (k=1, #f~, f[k, 1] = 5*(f[k, 1]+1)); factorback(f); } \\ Michel Marcus, May 21 2016 CROSSREFS Cf. A001222, A003959, A165826. Sequence in context: A043125 A043905 A072310 * A033708 A343821 A294171 Adjacent sequences: A166642 A166643 A166644 * A166646 A166647 A166648 KEYWORD nonn,easy,mult AUTHOR Jaroslav Krizek, Oct 18 2009 STATUS approved

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Last modified September 16 17:53 EDT 2024. Contains 375976 sequences. (Running on oeis4.)