A334971 a(n) is the least prime p such that p+2 is divisible by n-th prime.

2, 7, 3, 5, 31, 11, 83, 17, 67, 317, 29, 109, 367, 41, 139, 157, 293, 59, 199, 211, 71, 709, 911, 443, 677, 503, 101, 2459, 107, 337, 379, 653, 409, 137, 743, 149, 1097, 487, 499, 863, 1609, 179, 571, 191, 983, 197, 631, 1559, 6581, 227, 1163, 1193, 239, 751

Offset: 1

Author

Zak Seidov, May 18 2020

Keywords

• nonn

Examples

			a(1) = 2 because 2+2=4 is divisible by 2 (1st prime),
a(2) = 7 because 7+2=9 is divisible by 3 (2nd prime),
a(3) = 3 because 3+2=5 is divisible by 5 (3rd prime).
		

Links

• Zak Seidov, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A052147.

Programs

PARI

a(n) = my(p=2); while ((p+2) % prime(n), p=nextprime(p+1)); p; \\ Michel Marcus, May 18 2020