A167357 Totally multiplicative sequence with a(p) = (p-2)*(p+3) = p^2+p-6 for prime p.

1, 0, 6, 0, 24, 0, 50, 0, 36, 0, 126, 0, 176, 0, 144, 0, 300, 0, 374, 0, 300, 0, 546, 0, 576, 0, 216, 0, 864, 0, 986, 0, 756, 0, 1200, 0, 1400, 0, 1056, 0, 1716, 0, 1886, 0, 864, 0, 2250, 0, 2500, 0, 1800, 0, 2856, 0, 3024, 0, 2244, 0, 3534, 0, 3776, 0, 1800

Offset

1,3

Links

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

Formula

Multiplicative with a(p^e) = ((p-2)*(p+3))^e. If n = Product p(k)^e(k) then a(n) = Product ((p(k)-2)*(p(k)+3))^e(k).

a(2k) = 0 for k >= 1.

a(n) = A166586(n) * A166591(n).

Sum_{k=1..n} a(k) ~ c * n^3, where c = (2/Pi^2) / Product_{p prime} (1 - 2/p^2 + 5/p^3 + 6/p^4) = 0.1449357432... . - Amiram Eldar, Dec 15 2022

Mathematica

a[1] = 1; a[n_] := (fi = FactorInteger[n]; Times @@ ((fi[[All, 1]] - 2)^fi[[All, 2]])); b[1] = 1; b[n_] := (fi = FactorInteger[n]; Times @@ ((fi[[All, 1]] + 3)^fi[[All, 2]])); Table[a[n]*b[n], {n, 1, 100}] (* G. C. Greubel, Jun 11 2016 *)

Crossrefs

Cf. A166586, A166591.

Sequence in context: A292497 A082731 A272673 * A064381 A062254 A028849

Adjacent sequences: A167354 A167355 A167356 * A167358 A167359 A167360

Keyword

nonn,mult

Author

Jaroslav Krizek, Nov 01 2009

Status

approved