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A167317 Totally multiplicative sequence with a(p) = 7*(p-3) for prime p. 1
1, -7, 0, 49, 14, 0, 28, -343, 0, -98, 56, 0, 70, -196, 0, 2401, 98, 0, 112, 686, 0, -392, 140, 0, 196, -490, 0, 1372, 182, 0, 196, -16807, 0, -686, 392, 0, 238, -784, 0, -4802, 266, 0, 280, 2744, 0, -980, 308, 0, 784, -1372 (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) = (7*(p-3))^e. If n = Product p(k)^e(k) then a(n) = Product (7*(p(k)-3))^e(k). a(3k) = 0 for k >= 1. a(n) = A165828(n) * A166589(n) = 7^bigomega(n) * A166589(n) = 7^A001222(n) * A166589(n).

MATHEMATICA

a[1] = 1; a[n_] := (fi = FactorInteger[n]; Times @@ ((fi[[All, 1]] - 3)^fi[[All, 2]])); Table[a[n]*7^PrimeOmega[n], {n, 1, 100}] (* G. C. Greubel, Jun 09 2016 *)

CROSSREFS

Sequence in context: A222322 A228762 A046273 * A266436 A240822 A240810

Adjacent sequences:  A167314 A167315 A167316 * A167318 A167319 A167320

KEYWORD

sign,mult

AUTHOR

Jaroslav Krizek, Nov 01 2009

STATUS

approved

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Last modified January 20 18:38 EST 2022. Contains 350472 sequences. (Running on oeis4.)