A057662 Smallest prime q such that q+2^prime(n) is a prime, where prime(n) is the n-th prime.

3, 3, 5, 3, 5, 17, 29, 53, 11, 11, 11, 29, 71, 29, 5, 5, 131, 197, 3, 11, 29, 23, 89, 29, 359, 149, 239, 239, 881, 281, 29, 3449, 197, 683, 389, 683, 101, 1283, 83, 191, 1181, 197, 5, 71, 107, 101, 71, 4001, 1433, 251, 431, 29, 1361, 89, 509, 83, 2459, 941, 101, 197

Offset

1,1

Comments

n=6, prime(6)=13, 8192+17=8209 is a prime but 8192+2,8182+3,...,8192+13 are not, so a(6)=17

Links

Table of n, a(n) for n=1..60.

Formula

a(n) = A056206(A000040(n)).

Prog

(PARI) a(n) = my(P=2^prime(n), q=2); while (!isprime(P+q), q = nextprime(q+1)); q; \\ Michel Marcus, Mar 04 2022

Crossrefs

Cf. A056206, A056208.

Sequence in context: A239931 A033558 A046217 * A015971 A163167 A243729

Adjacent sequences: A057659 A057660 A057661 * A057663 A057664 A057665

Keyword

nonn

Author

Labos Elemer, Oct 16 2000

Status

approved