A048862 Number of primes in the reduced residue system of n-th primorial number (=A002110(n)).

0, 0, 1, 7, 42, 338, 3242, 42324, 646021, 12283522, 300369786, 8028642999, 259488750732, 9414916809082, 362597750396726, 15397728527812843, 742238179058722875, 4006896850151069172

Offset

0,4

Links

Table of n, a(n) for n=0..17.

Formula

a(n) = A000849(n) - n = A000720((A002110(n)) - A001221(A002110(n)).

Example

n=3, 3rd primorial is 30, EulerPhi(30)=8, a(3)=8-1=7 since 1 is regarded here a nonprime. See A048597. n=4, 4th primorial is 210, size of its reduced residue system(RRS) is 48 of which 42 is prime and 6 is either composite or 1.

Crossrefs

Cf. A002110, A000010, A000720, A048597, A007625, A048863.

Sequence in context: A073506 A025593 A218124 * A208943 A209071 A174224

Adjacent sequences: A048859 A048860 A048861 * A048863 A048864 A048865

Keyword

more,nonn

Author

Labos Elemer

Extensions

a(0) prepended and extended by Max Alekseyev, Feb 22 2016

Status

approved