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A112724
a(n) is the smallest number m such that the first n primes are all distinct prime divisors of m and for i=1,2,...,n prime(i)*m+1 is prime.
3
2, 6, 600, 210, 866250, 15732957240, 156225655145328088320, 7121261709511950
OFFSET
1,1
COMMENTS
Next term is greater than 3*10^15.
a(9) > 10^30. - Donovan Johnson, Nov 15 2009
a(9) > 10^50. - Giovanni Resta, Apr 17 2017
EXAMPLE
a(6)=15732957240 because {2,3,5,7,11,13}={prime(1),prime(2),..., prime(6)} is the set of all prime divisors of 15732957240;
all six numbers 2*15732957240+1,3*15732957240+1,5*15732957240+1, 7*15732957240+1,11*15732957240+1 & 13*15732957240+1 are prime and 15732957240 is the first number with such properties.
CROSSREFS
KEYWORD
hard,nonn
AUTHOR
Farideh Firoozbakht, Nov 05 2005
EXTENSIONS
a(7)-a(8) from Donovan Johnson, Nov 15 2009
STATUS
approved