A368202 Least k such that 6*n*k+1 is a prime.

1, 1, 1, 3, 1, 1, 1, 2, 2, 1, 1, 1, 1, 4, 2, 1, 1, 1, 2, 2, 1, 3, 1, 3, 1, 1, 1, 2, 2, 1, 2, 1, 1, 2, 1, 2, 1, 1, 4, 1, 3, 3, 4, 5, 1, 1, 1, 2, 3, 2, 1, 1, 10, 4, 1, 1, 6, 1, 2, 5, 1, 1, 1, 2, 3, 1, 4, 1, 2, 1, 2, 1, 1, 4, 4, 1, 1, 2, 3, 7, 1, 6, 1, 2, 2, 2

Offset: 1

Author

Robert Price, Dec 16 2023

Keywords

• nonn

Links

• Robert Price, Table of n, a(n) for n = 1..5000

Crossrefs

Cf. A016014, A024899.

A070850 lists the corresponding primes.

Programs

Mathematica

A368202 = {};
Do[k=1; While[!PrimeQ[9 n k+1], k++]; AppendTo[A368202, k], {n, 86}];
A368202

PARI

a(n) = my(k=1); while (!isprime(6*n*k+1), k++); k; \\ Michel Marcus, Dec 16 2023