A054641 GCD of divisor-sum of primorials and primorials itself: a(n) = gcd(A002110(n), A000203(A002110(n))).

1, 6, 6, 6, 6, 42, 42, 210, 210, 210, 210, 3990, 3990, 43890, 43890, 43890, 43890, 1360590, 23130030, 23130030, 855811110, 855811110, 855811110, 855811110, 855811110, 855811110, 11125544430, 11125544430, 11125544430, 11125544430

Offset: 1

Author

Labos Elemer, May 15 2000

Keywords

• nonn

Comments

Values are repeated for several arguments: observed from 1 to 8 times below n=100. Sites of jump seems not so regular.

From a sufficiently high value of n, A002110(n) divides the terms. E.g., from n=27, A002110(8) divides the values of this sequences.

Links

• Index to divisibility sequences

Crossrefs

Cf. A002110, A000203, A028815, A054640, A054642.

Programs

PARI

a(n)=gcd(prod(i=1,n,prime(i)),prod(i=1,n,prime(i)+1)) \\ Charles R Greathouse IV, Feb 19 2013