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A167315 Totally multiplicative sequence with a(p) = 5*(p-3) for prime p. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

FORMULA

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. a(n) = A165826(n) * A166589(n) = 5^bigomega(n) * A166589(n) = 5^A001222(n) * A166589(n).

MATHEMATICA

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 *)

CROSSREFS

Sequence in context: A022665 A114205 A316464 * A167362 A070611 A047769

Adjacent sequences:  A167312 A167313 A167314 * A167316 A167317 A167318

KEYWORD

sign,mult

AUTHOR

Jaroslav Krizek, Nov 01 2009

STATUS

approved

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Last modified August 15 13:27 EDT 2020. Contains 336504 sequences. (Running on oeis4.)