OFFSET
1,1
COMMENTS
a(6) > 10^9.
EXAMPLE
884037 = 3*7*11*43*89 and (1 + 884037)/2, (3 + 7*11*43*89)/2,
(7 + 3*11*43*89)/2, (11 + 3*7*43*89)/2, (43 + 3*7*11*89)/2, (89 + 3*7*11*43)/2,
(3*7 + 11*43*89)/2, (3*11 + 7*43*89)/2, (3*43 + 7*11*89)/2,(3*89 + 7*11*43)/2,
(7*11 + 3*43*89)/2, (7*43 + 3*7*89)/2, (7*89 + 3*7*43)/2, (11*43 + 3*7*89)/2,
(11*89 + 3*7*43)/2, (43*89 + 3*7*11)/2 are all primes and 884037 is the smallest such integer, so a(1) = 884037.
CROSSREFS
KEYWORD
hard,nonn
AUTHOR
Kok Seng Chua (chuakokseng(AT)hotmail.com), Mar 05 2007
EXTENSIONS
a(6)-a(18) from Donovan Johnson, Oct 12 2008
STATUS
approved