A338543 -id:A338543 - cp's OEIS frontend

A341805 Numbers k such that (product of first k primes)-1 is divisible by the (k+1)-th prime.

0, 2, 4, 9823712

Offset: 1

Jeppe Stig Nielsen, Feb 20 2021

			4 is a member because 2*3*5*7-1 (product of first 4 primes, minus one) is divisible by the 5th prime, 11.
9823712 is a member because 2*3*5*...*176078267-1 is divisible by 176078293, where 176078267 is the 9823712th prime.

Cf. A079276, A081618, A338543, A341804, A341812.

isok(k) = ((vecprod(primes(k)) - 1) % prime(k+1)) == 0; \\ Michel Marcus, Mar 03 2021

a(n) = A000720(A341804(n)) - 1.

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

Original entry on oeis.org

557, 248137, 4085791, 519807973

Offset: 1

Martin Ehrenstein, Jan 16 2021

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

Norman Luhn, Prime Curios! 557

Cf. A338543, A062347, A034386.

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

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A341805 Numbers k such that (product of first k primes)-1 is divisible by the (k+1)-th prime.

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

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