A295111 Primes p such that 2^p - p is also a prime.

2, 3, 13, 19, 481801

Offset

1,1

Comments

a(6) > 1061095.

Intersection of A000040 and A048744.

Since numbers other than 3 that are congruent to 3 mod 6 are composite, for n > 2, a(n) is congruent to 1 mod 6 (see comments by Iain Fox in A048744).

Links

Table of n, a(n) for n=1..5.

Example

p=13, 2^13 - 13 = 8179 is prime.

Prog

(PARI) lista(nn) = forprime(p=2, nn, if(ispseudoprime(2^p - p), print1(p, ", ")))

Crossrefs

Cf. A000325, A081296, A048744, A057663, A057673.

Sequence in context: A234366 A084958 A249573 * A229117 A295722 A037392

Adjacent sequences: A295108 A295109 A295110 * A295112 A295113 A295114

Keyword

hard,more,nonn

Author

Iain Fox, Nov 14 2017

Status

approved