A366810 a(n) = phi(prime(n)#-1) where phi is the Euler totient function and p# is the product of all the primes from 2 to p inclusive.

1, 4, 28, 180, 2308, 30028, 502080, 9458176, 215401680, 6387798300, 200559384576, 7369724839680, 304250263527208, 13082668722666720, 611670442764457840, 32588685419205242880, 1922760350056947598944, 117190066177425882515040, 7810108077410021826572976

Offset: 1

Author

Sean A. Irvine, Oct 23 2023

Keywords

• nonn

Crossrefs

Cf. A057588, A000010, A171989, A366759.

Programs

Maple

seq(numtheory[phi](mul(ithprime(k), k=1..n)-1), n=1..30);

PARI

a(n)=eulerphi(prod(k=1,n,prime(k))-1)

Formula

a(n) = A000010(A057588(n)).