A122256 Number of numbers <= n with 3-smooth Euler's totient (A000010).

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, 23, 24, 24, 25, 25, 26, 26, 27, 28, 29, 30, 31, 32, 33, 33, 34, 34, 34, 35, 35, 35, 36, 36, 36, 37, 38, 38, 39, 39, 40, 41, 41, 41, 42, 42, 42, 43, 44, 45, 45, 45, 46, 46, 47, 47, 48

Offset: 1

Author

Reinhard Zumkeller, Aug 29 2006

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Partial sums of A122255.

Cf. A000010, A003586, A071521.

Programs

Mathematica

b[n_] := Boole[FactorInteger[EulerPhi[n]][[-1, 1]] <= 3];
Table[b[n], {n, 1, 100}] // Accumulate (* Jean-François Alcover, Oct 14 2021 *)

PARI

issm(n) = {my(e = eulerphi(n >> valuation(n, 2))); e >>= valuation(e, 2); e == 3^valuation(e, 3);}
list(lim) = {my(s = 0); for(n = 1, lim, s += issm(n); print1(s, ", "));} \\ Amiram Eldar, May 14 2025