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A123921
Primes of form p*q - 2 where p and q are consecutive primes.
10
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
OFFSET
1,1
EXAMPLE
211*223-2 = 47051.
MAPLE
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;
MATHEMATICA
Select[Times@@@Partition[Prime[Range[1500]], 2, 1]-2, PrimeQ] (* Harvey P. Dale, Feb 23 2012 *)
PROG
(Haskell)
a123921 n = a123921_list !! (n-1)
a123921_list = filter ((== 1) . a010051) $
map (flip (-) 2) $ zipWith (*) a000040_list (tail a000040_list)
-- Reinhard Zumkeller, Nov 11 2011
(PARI) p=2; forprime(q=3, 1e5, if(isprime(t=p*q-2), print1(t", ")); p=q) \\ Charles R Greathouse IV, Apr 29 2015
CROSSREFS
Sequence in context: A176183 A241879 A185408 * A145716 A124990 A013752
KEYWORD
nice,nonn
AUTHOR
Ville Saalo (vsaalo(AT)iki.fi), Nov 19 2006
STATUS
approved