A324657 a(n) is the number of successive primorials A002110(i) larger than prime(n) that need to be tried before sum prime(n)+A002110(i) is found to be composite.

0, 0, 1, 1, 1, 2, 2, 0, 3, 4, 2, 0, 5, 0, 2, 1, 1, 3, 3, 2, 5, 0, 3, 0, 1, 2, 1, 4, 0, 0, 2, 0, 2, 1, 2, 0, 3, 2, 0, 1, 1, 0, 1, 0, 0, 1, 2, 0, 0, 2, 1, 2, 3, 0, 0, 0, 1, 0, 0, 1, 4, 0, 1, 2, 0, 0, 0, 4, 1, 1, 1, 0, 1, 2, 1, 1, 1, 3, 2, 1, 2, 1, 1, 0, 2, 1, 0, 1, 0, 0, 2, 4, 2, 1, 0, 0, 3, 0, 4, 1, 3, 0, 0, 1, 0

Offset

1,6

Comments

See comments and examples in A324656.

Links

Antti Karttunen, Table of n, a(n) for n = 1..25000

Index entries for sequences related to primorial numbers

Formula

a(n) = A324656(A000040(n)).

Prog

(PARI)
A002110(n) = prod(i=1, n, prime(i));
A235224(n, p=2) = if(!n, n, 1+A235224(n\p, nextprime(p+1)));
A324656(n) = { my(k=0, b=A235224(n)); while(isprime(n+A002110(b+k)), k++); (k); };
A324657(n) = A324656(prime(n));

Crossrefs

Cf. A000040, A002110, A324656.

Sequence in context: A239292 A262879 A278482 * A369524 A339422 A367746

Adjacent sequences: A324654 A324655 A324656 * A324658 A324659 A324660

Keyword

nonn

Author

Antti Karttunen, Mar 11 2019

Status

approved