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 A122256 #15 May 15 2025 00:56:44
%S A122256 1,2,3,4,5,6,7,8,9,10,10,11,12,13,14,15,16,17,18,19,20,20,20,21,21,22,
%T A122256 23,24,24,25,25,26,26,27,28,29,30,31,32,33,33,34,34,34,35,35,35,36,36,
%U A122256 36,37,38,38,39,39,40,41,41,41,42,42,42,43,44,45,45,45,46,46,47,47,48
%N A122256 Number of numbers <= n with 3-smooth Euler's totient (A000010).
%H A122256 Amiram Eldar, <a href="/A122256/b122256.txt">Table of n, a(n) for n = 1..10000</a>
%t A122256 b[n_] := Boole[FactorInteger[EulerPhi[n]][[-1, 1]] <= 3];
%t A122256 Table[b[n], {n, 1, 100}] // Accumulate (* _Jean-François Alcover_, Oct 14 2021 *)
%o A122256 (PARI) issm(n) = {my(e = eulerphi(n >> valuation(n, 2))); e >>= valuation(e, 2); e == 3^valuation(e, 3);}
%o A122256 list(lim) = {my(s = 0); for(n = 1, lim, s += issm(n); print1(s, ", "));} \\ _Amiram Eldar_, May 14 2025
%Y A122256 Partial sums of A122255.
%Y A122256 Cf. A000010, A003586, A071521.
%K A122256 nonn
%O A122256 1,2
%A A122256 _Reinhard Zumkeller_, Aug 29 2006