A146524 a(n) is the largest nonnegative integer m such that 2*n*k+1 is prime for all k where 1<=k<=m. a(n) = 0 if 2n+1 is composite.

3, 1, 3, 0, 1, 1, 0, 1, 2, 0, 1, 0, 0, 1, 2, 0, 0, 3, 0, 1, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 2, 0, 1, 0, 0, 1, 0, 0, 0, 2, 0, 1, 1, 0, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 2, 0, 0, 0, 0, 1, 1, 0, 0, 2, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 1, 2, 0, 0, 0, 0, 0, 3

Offset

1,1

Links

Table of n, a(n) for n=1..105.

Example

For n = 3: 2*3*1 +1 = 7, which is prime. 2*3*2 + 1 = 13, which is prime. 2*3*3 + 1 = 19, which is prime. But 2*3*4 + 1 = 25, which is composite. So a(3) = 3, because there are 3 primes in the arithmetic sequence before hitting a composite.

Crossrefs

A146525

Sequence in context: A143783 A179175 A274635 * A179656 A167274 A201679

Adjacent sequences: A146521 A146522 A146523 * A146525 A146526 A146527

Keyword

nonn

Author

Leroy Quet, Oct 30 2008

Extensions

Extended by Ray Chandler, Nov 01 2008

Status

approved