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 A167319 #11 Oct 22 2023 00:49:55 %S A167319 1,-9,0,81,18,0,36,-729,0,-162,72,0,90,-324,0,6561,126,0,144,1458,0, %T A167319 -648,180,0,324,-810,0,2916,234,0,252,-59049,0,-1134,648,0,306,-1296, %U A167319 0,-13122,342,0,360,5832,0,-1620,396,0,1296,-2916,0,7290,450,0,1296,-26244 %N A167319 Totally multiplicative sequence with a(p) = 9*(p-3) for prime p. %H A167319 G. C. Greubel, <a href="/A167319/b167319.txt">Table of n, a(n) for n = 1..1000</a> %F A167319 Multiplicative with a(p^e) = (9*(p-3))^e. If n = Product p(k)^e(k) then a(n) = Product (9*(p(k)-3))^e(k). %F A167319 a(3k) = 0 for k >= 1. %F A167319 a(n) = A165830(n) * A166589(n) = 9^bigomega(n) * A166589(n) = 9^A001222(n) * A166589(n). %t A167319 a[1] = 1; a[n_] := (fi = FactorInteger[n]; Times @@ ((fi[[All, 1]] - 3)^fi[[All, 2]])); Table[a[n]*9^PrimeOmega[n], {n, 1, 100}] (* _G. C. Greubel_, Jun 09 2016 *) %t A167319 f[p_, e_] := (9*(p-3))^e; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* _Amiram Eldar_, Oct 22 2023 *) %Y A167319 Cf. A001222, A165830, A166589. %K A167319 sign,easy,mult %O A167319 1,2 %A A167319 _Jaroslav Krizek_, Nov 01 2009