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 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. 0
 1, 4, 28, 180, 2308, 30028, 502080, 9458176, 215401680, 6387798300, 200559384576, 7369724839680, 304250263527208, 13082668722666720, 611670442764457840, 32588685419205242880, 1922760350056947598944, 117190066177425882515040, 7810108077410021826572976 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..19. FORMULA a(n) = A000010(A057588(n)). MAPLE seq(numtheory[phi](mul(ithprime(k), k=1..n)-1), n=1..30); PROG (PARI) a(n)=eulerphi(prod(k=1, n, prime(k))-1) CROSSREFS Cf. A057588, A000010, A171989, A366759. Sequence in context: A181895 A264707 A216211 * A219405 A001396 A155611 Adjacent sequences: A366807 A366808 A366809 * A366811 A366812 A366813 KEYWORD nonn AUTHOR Sean A. Irvine, Oct 23 2023 STATUS approved

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Last modified August 10 15:21 EDT 2024. Contains 375056 sequences. (Running on oeis4.)