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(Product of successive primes minus 2) divided by 7 is prime.
1

%I #6 Sep 03 2015 11:45:29

%S 4127,49727,212627,565727,697727,1152227,3102227,3486227,5742227,

%T 7488227,8078627,8848127,10837727,14200127,23041427,41870627,50437727,

%U 59044127,68766227,70088927,91008227,115141727,118573727,122641427

%N (Product of successive primes minus 2) divided by 7 is prime.

%H Harvey P. Dale, <a href="/A125502/b125502.txt">Table of n, a(n) for n = 1..1000</a>

%e 167*173 = 28891, (28891-2)/7 = 4127 the first entry.

%t Select[(Times@@@Partition[Prime[Range[5000]],2,1]-2)/7,PrimeQ] (* _Harvey P. Dale_, Sep 03 2015 *)

%o (PARI) g(n,p) = { for(x=1,n, y=prime(x)*prime(x+1)-2; if(y%p==0,if(isprime(y/p), print1(y/p",")))) }

%Y Cf. A123921.

%K easy,nonn

%O 1,1

%A _Cino Hilliard_, Dec 28 2006

%E Typo in example corrected by _Harvey P. Dale_, Sep 03 2015