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A341805
Numbers k such that (product of first k primes)-1 is divisible by the (k+1)-th prime.
4
0, 2, 4, 9823712
OFFSET
1,2
FORMULA
a(n) = A000720(A341804(n)) - 1.
EXAMPLE
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.
PROG
(PARI) isok(k) = ((vecprod(primes(k)) - 1) % prime(k+1)) == 0; \\ Michel Marcus, Mar 03 2021
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Jeppe Stig Nielsen, Feb 20 2021
STATUS
approved