A092702 - OEIS

A092702

If P(n) is the product of the first n Mersenne primes, then a(n) is the smallest positive integer such that 2*a(n)*P(n)-1 is prime.

1, 1, 1, 8, 1, 12, 4, 33, 3, 19, 22, 71, 58, 10, 230, 1487, 2887, 555, 1260, 1711, 377, 343

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OFFSET

1,4

COMMENTS

a(2) starts sequence A092527

LINKS

EXAMPLE

a(4) = 8: 2*8*(2^2-1)*(2^3-1)*(2^5-1)*(2^7-1)-1 = 2*8*3*7*31*127-1 = 1322832-1 = 1322831, which is prime.

CROSSREFS

KEYWORD

nonn

AUTHOR

Ray G. Opao, Apr 12 2004

STATUS

approved