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A167350 Totally multiplicative sequence with a(p) = (p+1)*(p-2) = p^2-p-2 for prime p. 1
1, 0, 4, 0, 18, 0, 40, 0, 16, 0, 108, 0, 154, 0, 72, 0, 270, 0, 340, 0, 160, 0, 504, 0, 324, 0, 64, 0, 810, 0, 928, 0, 432, 0, 720, 0, 1330, 0, 616, 0, 1638, 0, 1804, 0, 288, 0, 2160, 0, 1600, 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) = ((p+1)*(p-2))^e. If n = Product p(k)^e(k) then a(n) = Product ((p(k)+1)*(p(k)-2))^e(k). a(2k) = 0 for k >= 1, a(n) = A003959(n) * A166586(n).

MATHEMATICA

a[1] = 1; a[n_] := (fi = FactorInteger[n]; Times @@ ((fi[[All, 1]] + 1)^fi[[All, 2]])); b[1] = 1; b[n_] := (fi = FactorInteger[n]; Times @@ ((fi[[All, 1]] - 2)^fi[[All, 2]])); Table[a[n]*b[n], {n, 1, 100}] (* G. C. Greubel, Jun 10 2016 *)

CROSSREFS

Sequence in context: A137279 A233807 A302771 * A215669 A244310 A334705

Adjacent sequences:  A167347 A167348 A167349 * A167351 A167352 A167353

KEYWORD

nonn,mult

AUTHOR

Jaroslav Krizek, Nov 01 2009

STATUS

approved

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Last modified February 26 17:22 EST 2021. Contains 341632 sequences. (Running on oeis4.)