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 A166635 #14 Feb 05 2025 07:51:19
%S A166635 1,5,10,25,20,50,30,125,100,100,50,250,60,150,200,625,80,500,90,500,
%T A166635 300,250,110,1250,400,300,1000,750,140,1000,150,3125,500,400,600,2500,
%U A166635 180,450,600,2500,200,1500,210,1250,2000,550,230,6250,900,2000
%N A166635 Totally multiplicative sequence with a(p) = 5*(p-1) for prime p.
%H A166635 G. C. Greubel, <a href="/A166635/b166635.txt">Table of n, a(n) for n = 1..10000</a>
%F A166635 Multiplicative with a(p^e) = (5*(p-1))^e. If n = Product p(k)^e(k) then a(n) = Product (5*(p(k)-1))^e(k).
%F A166635 a(n) = A165826(n) * A003958(n) = 5^bigomega(n) * A003958(n) = 5^A001222(n) * A003958(n).
%t A166635 DirichletInverse[f_][1] = 1/f[1]; DirichletInverse[f_][n_] :=
%t A166635 DirichletInverse[f][n] = -1/f[1]*Sum[f[n/d]*DirichletInverse[f][d], {d, Most[Divisors[n]]}]; muphi[n_] := MoebiusMu[n]*EulerPhi[n]; a[m_] := DirichletInverse[muphi][m]; Table[a[m]*5^(PrimeOmega[m]), {m, 1, 100}] (* _G. C. Greubel_, May 20 2016 *)
%t A166635 a[p_?PrimeQ] := a[p] = 5*(p-1); a[1] = 1; a[n_] := ({pp, ee} = FactorInteger[n] // Transpose; Times @@ ((a /@ pp)^ee)); Array[a, 50] (* _Jean-François Alcover_, Feb 02 2018 *)
%Y A166635 Cf. A001222, A003958, A165826, A166633, A166634.
%K A166635 nonn,easy,mult
%O A166635 1,2
%A A166635 _Jaroslav Krizek_, Oct 18 2009