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

1,2

Links

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

Mathematica

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

Prog

(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

Crossrefs

Partial sums of A122255.

Cf. A000010, A003586, A071521.

Sequence in context: A071604 A337769 A061069 * A122262 A172268 A017895

Adjacent sequences: A122253 A122254 A122255 * A122257 A122258 A122259

Keyword

nonn

Author

Reinhard Zumkeller, Aug 29 2006

Status

approved