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Number of noncomposites in the reduced residue system of n-th primorial number, A002110(n).
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%I #41 Sep 06 2023 20:42:37

%S 1,2,8,43,339,3243,42325,646022,12283523,300369787,8028643000,

%T 25948875073,9414916809083,362597750396727,15397728527812844,

%U 742238179058722876,40068968501510691878

%N Number of noncomposites in the reduced residue system of n-th primorial number, A002110(n).

%F a(n) = pi(primorial(n)) - n + 1, n > 0.

%F a(n) = A000849(n) - n + 1, n > 0.

%F a(n) = A048862(n) + 1. - _Michel Marcus_, Oct 03 2016

%t Primorial[n_] := Product[Prime[j], {j, 1, n}];

%t Table[PrimePi[Primorial[n]] - n + 1, {n, 1, 12}]

%o (PARI) a(n) = primepi(prod(k=1,n,prime(k))) - n + 1; \\ _Michel Marcus_, Oct 03 2016

%Y Cf. A000849, A002110, A048862.

%K nonn,more

%O 1,2

%A _Andres Cicuttin_, Sep 29 2016

%E Definition aligned with formulas and data by _Peter Munn_, Sep 06 2023