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A123921
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Primes of form p*q - 2 where p and q are consecutive primes.
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10
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13, 25589, 47051, 67589, 136889, 313589, 960389, 1005971, 1932017, 2301251, 2362331, 6100889, 6310061, 6901091, 7745051, 8236817, 9332987, 10956089, 13104389, 16850987, 19009589, 19201841, 19386371, 19998701, 20566079
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OFFSET
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1,1
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LINKS
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EXAMPLE
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211*223-2 = 47051.
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MAPLE
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with (numtheory): for n from 1 to 1000 do if (tau(ithprime(n)*ithprime(n+1)-2)=2) then print(ithprime(n), ithprime(n+1), ithprime(n)*ithprime(n+1)-2); fi; od;
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MATHEMATICA
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Select[Times@@@Partition[Prime[Range[1500]], 2, 1]-2, PrimeQ] (* Harvey P. Dale, Feb 23 2012 *)
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PROG
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(Haskell)
a123921 n = a123921_list !! (n-1)
a123921_list = filter ((== 1) . a010051) $
map (flip (-) 2) $ zipWith (*) a000040_list (tail a000040_list)
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CROSSREFS
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KEYWORD
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nice,nonn
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AUTHOR
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Ville Saalo (vsaalo(AT)iki.fi), Nov 19 2006
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STATUS
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approved
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