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 A166643 #18 Feb 06 2025 08:22:59
%S A166643 1,9,12,81,18,108,24,729,144,162,36,972,42,216,216,6561,54,1296,60,
%T A166643 1458,288,324,72,8748,324,378,1728,1944,90,1944,96,59049,432,486,432,
%U A166643 11664,114,540,504,13122,126,2592,132,2916,2592,648,144,78732,576,2916
%N A166643 Totally multiplicative sequence with a(p) = 3*(p+1) for prime p.
%H A166643 G. C. Greubel, <a href="/A166643/b166643.txt">Table of n, a(n) for n = 1..10000</a>
%F A166643 Multiplicative with a(p^e) = (3*(p+1))^e. If n = Product p(k)^e(k) then a(n) = Product (3*(p(k)+1))^e(k).
%F A166643 a(n) = A165824(n) * A003959(n) = 3^bigomega(n) * A003959(n) = 3^A001222(n) * A003959(n).
%t A166643 a[1] = 1; a[n_] := (fi = FactorInteger[n]; Times @@ ((fi[[All, 1]] + 1)^fi[[All, 2]])); Table[a[n]*3^(PrimeOmega[n]), {n, 1, 100}] (* _G. C. Greubel_, May 20 2016 *)
%t A166643 f[p_, e_] := (3*(p+1))^e; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* _Amiram Eldar_, Oct 17 2023 *)
%o A166643 (PARI) a(n) = {my(f = factor(n)); for (k=1, #f~, f[k,1] = 3*(f[k,1]+1)); factorback(f);} \\ _Michel Marcus_, May 21 2016
%Y A166643 Cf. A001222, A003959, A165824.
%K A166643 nonn,easy,mult
%O A166643 1,2
%A A166643 _Jaroslav Krizek_, Oct 18 2009