This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A167347 #15 Dec 15 2022 06:17:39
%S A167347 1,-1,0,1,8,0,24,-1,0,-8,80,0,120,-24,0,1,224,0,288,8,0,-80,440,0,64,
%T A167347 -120,0,24,728,0,840,-1,0,-224,192,0,1224,-288,0,-8,1520,0,1680,80,0,
%U A167347 -440,2024,0,576,-64
%N A167347 Totally multiplicative sequence with a(p) = (p-1)*(p-3) = p^2-4p+3 for prime p.
%H A167347 G. C. Greubel, <a href="/A167347/b167347.txt">Table of n, a(n) for n = 1..1000</a>
%F A167347 Multiplicative with a(p^e) = ((p-1)*(p-3))^e. If n = Product p(k)^e(k) then a(n) = Product ((p(k)-1)*(p(k)-3))^e(k).
%F A167347 a(3k) = 0 for k >= 1.
%F A167347 a(n) = A003958(n) * A166589(n).
%F A167347 Sum_{k=1..n} a(k) ~ c * n^3, where c = (2/Pi^2) / Product_{p prime} (1 + 3/p^2 + 1/p^3 - 3/p^4) = 0.06874072991... . - _Amiram Eldar_, Dec 15 2022
%t A167347 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]] - 3)^fi[[All, 2]])); Table[a[n]*b[n], {n, 1, 100}] (* _G. C. Greubel_, Jun 10 2016 *)
%Y A167347 Cf. A003958, A166589.
%K A167347 sign,mult
%O A167347 1,5
%A A167347 _Jaroslav Krizek_, Nov 01 2009