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A167346 Totally multiplicative sequence with a(p) = (p-1)*(p+2) = p^2+p-2 for prime p. 1
1, 4, 10, 16, 28, 40, 54, 64, 100, 112, 130, 160, 180, 216, 280, 256, 304, 400, 378, 448, 540, 520, 550, 640, 784, 720, 1000, 864, 868, 1120, 990, 1024, 1300, 1216, 1512, 1600, 1404, 1512, 1800, 1792, 1720, 2160, 1890, 2080, 2800, 2200, 2254, 2560, 2916, 3136 (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) = ((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(n) = A003958(n) * A166590(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: A112984 A191115 A073121 * A027430 A298031 A027425

Adjacent sequences:  A167343 A167344 A167345 * A167347 A167348 A167349

KEYWORD

nonn,mult

AUTHOR

Jaroslav Krizek, Nov 01 2009

STATUS

approved

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Last modified March 20 13:18 EDT 2019. Contains 321345 sequences. (Running on oeis4.)