A367132 a(n) = phi(A000058(n)) where phi is the Euler totient function and A000058 is Sylvester's sequence.

1, 2, 6, 42, 1656, 3263442, 10602458193600, 113418211994216207709696000, 12864938683276241891688635987477942287491075520480800, 164509411410546646527417252552411687615280114012485682055193015232979290788896945885448940165659663840000

Offset: 0

Author

Sean A. Irvine, Nov 05 2023

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 0..10
• Wikipedia, Sylvester's sequence: Divisibility and factorizations.

Crossrefs

Cf. A000058, A000010, A091335.

Programs

Mathematica

EulerPhi[a[0] = 2; a[k_] := a[k - 1]^2 - a[k - 1] + 1; Table[a[k], {k, 0, 9}]] (* Paul F. Marrero Romero, Nov 19 2023 *)

Formula

a(n) = A000010(A000058(n)).