A366760 a(n) = phi(n!+1), where phi is Euler's totient function (A000010).

1, 1, 2, 6, 20, 110, 612, 4970, 39600, 337680, 3298900, 39916800, 442155168, 6151996372, 83387930692, 1282826630160, 19089488332800, 355148307803520, 5427568925856000, 119931789135468100, 2432901890279317572, 49902667163053013232, 1073067539495604750240

Offset

0,3

Links

Table of n, a(n) for n=0..22.

Formula

a(n) = A000010(A038507(n)).

Mathematica

EulerPhi[Range[0, 25]!+1] (* Paolo Xausa, Oct 21 2023 *)

Prog

(PARI) {a(n) = eulerphi(n!+1)}
(Python)
from math import factorial
from sympy import totient
def A366760(n): return totient(factorial(n)+1) # Chai Wah Wu, Oct 20 2023

Crossrefs

Cf. A038507, A000010, A048855, A366759.

Sequence in context: A268562 A287009 A243252 * A136795 A074115 A013206

Adjacent sequences: A366757 A366758 A366759 * A366761 A366762 A366763

Keyword

nonn

Author

Sean A. Irvine, Oct 20 2023

Status

approved