A087575 - OEIS

A087575

Smallest prime p such that 2+p^n is a prime, or 0 if no such prime exists.

3, 3, 3, 3, 11, 0, 53, 3, 11, 3, 23, 0, 71, 3, 3, 0, 5, 0, 521, 0, 1847, 0, 41, 3, 71, 3, 59, 0, 191, 0, 71, 0, 827, 0, 761, 3, 1721, 0, 23, 0, 197, 0, 1229, 0, 59, 0, 1493, 0, 101, 0, 389, 0, 2381, 0, 3023, 0, 4691, 0, 6263, 0, 9719, 0, 3, 0, 2207, 0, 983, 0, 6701, 0, 239, 0, 347

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..73.

EXAMPLE

a(2)=a(3)=a(4)=3, as 3^2 + 2, 3^3 + 2, 3^4 + 2 are all prime.

PROG

(PARI) for(j=1, 50, forprime (i=1, 50000, if(isprime(i^j+2), print1(i, ", "); break())))

CROSSREFS

Sequence in context: A087576 A337328 A201700 * A001270 A029630 A342400

Adjacent sequences: A087572 A087573 A087574 * A087576 A087577 A087578