A340712 Primes p such that p divides (2 + product of primes < p).

557, 248137, 4085791, 519807973

Offset: 1

Author

Martin Ehrenstein, Jan 16 2021

Keywords

• nonn
• hard
• more

Examples

			557 is in the sequence because 2 + A034386(557 - 1) = 557 * 4627335992...5904782776 (220 digits).
		

Links

• Norman Luhn, Prime Curios! 557

Crossrefs

Cf. A338543, A062347, A034386.

Programs

Python

from sympy import nextprime
def aupto(limit):
  p, psharp = 3, 2
  while p <= limit:
    if (psharp+2)%p == 0: print(p, end=", ")
    psharp, p = psharp*p, nextprime(p)
aupto(500000) # Michael S. Branicky, Mar 24 2021