A368203 Least k such that 7*n*k+1 is a prime.

4, 2, 2, 1, 2, 1, 4, 2, 2, 1, 6, 4, 6, 2, 2, 1, 2, 1, 12, 2, 6, 3, 6, 2, 4, 3, 2, 1, 12, 1, 6, 2, 2, 1, 2, 3, 10, 6, 2, 1, 6, 3, 10, 2, 2, 3, 2, 1, 4, 2, 4, 3, 2, 1, 6, 8, 4, 6, 2, 1, 4, 3, 2, 1, 2, 1, 4, 2, 2, 1, 14, 2, 6, 5, 2, 3, 12, 1, 4, 5, 4, 3, 2, 6

Offset

1,1

Links

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

Mathematica

A368203 = {};
Do[k=1; While[!PrimeQ[7 n k+1], k++]; AppendTo[A368203, k], {n, 84}];
A368203

Prog

(PARI) a(n) = my(k=1); while (!isprime(7*n*k+1), k++); k; \\ Michel Marcus, Dec 16 2023

Crossrefs

Cf. A016014, A024905.

A070851 lists the corresponding primes.

Sequence in context: A250623 A123402 A205032 * A375735 A264752 A325527

Adjacent sequences: A368200 A368201 A368202 * A368204 A368205 A368206

Keyword

nonn

Author

Robert Price, Dec 16 2023

Status

approved