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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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
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

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Last modified March 28 14:38 EDT 2024. Contains 371254 sequences. (Running on oeis4.)