A167318 Totally multiplicative sequence with a(p) = 8*(p-3) for prime p.

1, -8, 0, 64, 16, 0, 32, -512, 0, -128, 64, 0, 80, -256, 0, 4096, 112, 0, 128, 1024, 0, -512, 160, 0, 256, -640, 0, 2048, 208, 0, 224, -32768, 0, -896, 512, 0, 272, -1024, 0, -8192, 304, 0, 320, 4096, 0, -1280, 352, 0, 1024, -2048, 0, 5120, 400, 0, 1024, -16384

Offset: 1

Author

Jaroslav Krizek, Nov 01 2009

Keywords

• sign
• easy
• mult

Links

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

Crossrefs

Cf. A001222, A165829, A166589.

Programs

Mathematica

a[1] = 1; a[n_] := (fi = FactorInteger[n]; Times @@ ((fi[[All, 1]] - 3)^fi[[All, 2]])); Table[a[n]*8^PrimeOmega[n], {n, 1, 100}] (* G. C. Greubel, Jun 09 2016 *)
f[p_, e_] := (8*(p-3))^e; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Oct 22 2023 *)

Formula

Multiplicative with a(p^e) = (8*(p-3))^e. If n = Product p(k)^e(k) then a(n) = Product (8*(p(k)-3))^e(k).

a(3k) = 0 for k >= 1.

a(n) = A165829(n) * A166589(n) = 8^bigomega(n) * A166589(n) = 8^A001222(n) * A166589(n).