OFFSET
1,1
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
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
KEYWORD
nice,nonn
AUTHOR
Ville Saalo (vsaalo(AT)iki.fi), Nov 19 2006
STATUS
approved