A366821 a(n) is phi(n^n-1) where phi is the Euler totient function.

2, 12, 128, 1400, 30240, 264992, 6635520, 141087744, 5890320000, 114117380608, 4662793175040, 99053063903040, 5470524984113280, 167080949856000000, 9208981628670443520, 413582117375670921216, 29531731481729468006400, 659473218553437863041320

Offset

2,1

Links

Robert G. Wilson v, Table of n, a(n) for n = 2..102

Formula

a(n) = A000010(A048861(n)).

Maple

a:= n-> numtheory[phi](n^n-1):
seq(a(n), n=2..20);  # Alois P. Heinz, Oct 26 2023

Mathematica

Array[EulerPhi[#^# - 1] &, 18, 2] (* Michael De Vlieger, Oct 24 2023 *)

Prog

(PARI) a(n) = eulerphi(n^n-1);

Crossrefs

Cf. A000010, A048861, A064447, A366822.

Sequence in context: A253282 A201470 A349268 * A003712 A143136 A214224

Adjacent sequences: A366818 A366819 A366820 * A366822 A366823 A366824

Keyword

nonn

Author

Sean A. Irvine, Oct 24 2023

Status

approved