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A167297 Totally multiplicative sequence with a(p) = 5*(p-2) for prime p. 1
1, 0, 5, 0, 15, 0, 25, 0, 25, 0, 45, 0, 55, 0, 75, 0, 75, 0, 85, 0, 125, 0, 105, 0, 225, 0, 125, 0, 135, 0, 145, 0, 225, 0, 375, 0, 175, 0, 275, 0, 195, 0, 205, 0, 375, 0, 225, 0, 625, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..1000

FORMULA

Multiplicative with a(p^e) = (5*(p-2))^e. If n = Product p(k)^e(k) then a(n) = Product (5*(p(k)-2))^e(k). a(2k) = 0 for k >= 1. a(n) = A165826(n) * A166586(n) = 5^bigomega(n) * A166586(n) = 5^A001222(n) * A166586(n).

MATHEMATICA

a[1] = 1; a[n_] := (fi = FactorInteger[n]; Times @@ ((fi[[All, 1]] - 2)^fi[[All, 2]])); Table[a[n]*5^PrimeOmega[n], {n, 1, 100}] (* G. C. Greubel, Jun 07 2016 *)

CROSSREFS

Sequence in context: A222946 A214121 A024418 * A290867 A027635 A291218

Adjacent sequences:  A167294 A167295 A167296 * A167298 A167299 A167300

KEYWORD

nonn,mult

AUTHOR

Jaroslav Krizek, Nov 01 2009

STATUS

approved

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Last modified June 25 12:55 EDT 2019. Contains 324352 sequences. (Running on oeis4.)