A366759 a(n) = phi(n!-1), where phi is Euler's totient function (A000010).

1, 4, 22, 96, 718, 5038, 38544, 329780, 3503640, 33166848, 479001598, 6223425864, 87178291198, 1168577230080, 20915909651520, 332351050332096, 6293831116536216, 121458761380686016, 2432882508925834560, 48311155748401677120, 1113688776127971818016

Offset

2,2

Links

Table of n, a(n) for n=2..22.

Formula

a(n) = A000010(A033312(n)).

Mathematica

EulerPhi[Range[2, 25]!-1] (* Paolo Xausa, Oct 21 2023 *)

Prog

(PARI) {a(n) = eulerphi(n!-1)}
(Python)
from math import factorial
from sympy import totient
def A366759(n): return totient(factorial(n)-1) # Chai Wah Wu, Oct 20 2023

Crossrefs

Cf. A033312, A000010, A048855, A366760.

Sequence in context: A036926 A079272 A197667 * A007901 A368289 A254861

Adjacent sequences: A366756 A366757 A366758 * A366760 A366761 A366762

Keyword

nonn

Author

Sean A. Irvine, Oct 20 2023

Status

approved