A256301 Least prime p such that p + k! is prime for all k = 2..n.

2, 3, 5, 5, 17, 107, 107, 107, 107, 82954517, 82954517, 79017245897, 79017245897, 1490524895687, 13101487760627087

Offset: 1

Author

M. F. Hasler, Apr 05 2015

Keywords

• nonn
• more

Comments

The function f(k;p) = p+(k+1)! could be called an example of a non-polynomial prime generating function.

Links

• Carlos Rivera, Puzzle 782. Prime-Generating non-polynomials, The Prime Puzzles & Problems Connection, April 4, 2015.

Programs

PARI

a(n)=forprime(p=1,,for(i=2,n,ispseudoprime(p+i!)||next(2));return(p))

Extensions

a(12)-a(14) from John Cerkan, Jul 28 2017

Erroneous a(12) deleted and new a(14) from Khalid Sabry, Jan 25 2020

a(15) from Giovanni Resta, Jan 28 2020