The On-Line Encyclopedia of Integer Sequences (OEIS)

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A087575

Smallest prime p such that 2+p^n is a prime, or 0 if no such prime exists.
(history; published version)

#6 by N. J. A. Sloane at Thu Dec 05 19:56:31 EST 2013

AUTHOR

_Amarnath Murthy (amarnath_murthy(AT)yahoo.com), _, Sep 17 2003

Discussion

Thu Dec 05

19:56

OEIS Server: https://oeis.org/edit/global/2075

#5 by Russ Cox at Sat Mar 31 13:20:50 EDT 2012

EXTENSIONS

More terms from _David Wasserman (wasserma(AT)spawar.navy.mil), _, Jun 08 2005

Discussion

Sat Mar 31

13:20

OEIS Server: https://oeis.org/edit/global/880

#4 by N. J. A. Sloane at Tue Jan 24 03:00:00 EST 2006

PROG

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

KEYWORD

nonn,new

nonn

#3 by N. J. A. Sloane at Tue Jul 19 03:00:00 EDT 2005

NAME

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

DATA

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

KEYWORD

more,nonn,new

nonn

EXTENSIONS

More terms from David Wasserman (wasserma(AT)spawar.navy.mil), Jun 08 2005

#2 by N. J. A. Sloane at Sat Jun 12 03:00:00 EDT 2004

DATA

2, 3, 3, 3, 3, 11, 53, 3, 11, 3, 23, 71, 3, 3, 5, 521, 1847, 41, 3, 71, 3, 59, 191, 71, 827, 761, 3, 1721, 23, 197, 1229, 59, 1493, 101

PROG

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

KEYWORD

more,nonn,new

EXTENSIONS

More terms from Mohammed Bouayoun (bouyao(AT)wanadoo.fr), Mar 14 2004

#1 by N. J. A. Sloane at Thu Feb 19 03:00:00 EST 2004

NAME

Smallest prime p such that p^n + 2 is a prime.

DATA

2, 3, 3, 3, 11

OFFSET

1,1

EXAMPLE

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

KEYWORD

more,nonn

AUTHOR

Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Sep 17 2003

STATUS

approved