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Search: id:A112724
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| A112724 |
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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. |
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+0
3
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| 2, 6, 600, 210, 866250, 15732957240, 156225655145328088320, 7121261709511950
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Next term is greater than 3*10^15.
a(9) > 10^30. [From Donovan Johnson (donovan.johnson(AT)yahoo.com), Nov 15 2009]
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LINKS
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Carlos Rivera, The Prime Puzzles & Problems connection.
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EXAMPLE
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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.
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CROSSREFS
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Cf. A092023, A092024, A112723.
Sequence in context: A114628 A135424 A132495 this_sequence A110795 A067107 A047690
Adjacent sequences: A112721 A112722 A112723 this_sequence A112725 A112726 A112727
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KEYWORD
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hard,nonn,new
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AUTHOR
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Farideh Firoozbakht (mymontain(AT)yahoo.com), Nov 05 2005
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EXTENSIONS
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a(7)-a(8) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Nov 15 2009
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