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A092728 Primes prime(k) such that prime(k)*prime(k+1)-4 is a prime. 1

%I #15 Jan 10 2019 18:48:23

%S 2,3,5,7,11,19,41,43,71,79,89,101,113,127,139,197,229,359,397,431,463,

%T 499,683,709,773,857,881,967,1009,1031,1109,1151,1213,1279,1297,1373,

%U 1423,1427,1447,1451,1559,1597,1607,1699,1783,1787,1823,1951,1993,2081

%N Primes prime(k) such that prime(k)*prime(k+1)-4 is a prime.

%H Robert Israel, <a href="/A092728/b092728.txt">Table of n, a(n) for n = 1..10000</a>

%p Primes:= [seq(ithprime(i),i=1..1000)]:

%p Primes[select(t -> isprime(Primes[t]*Primes[t+1]-4), [$1..999])]; # _Robert Israel_, Jan 10 2019

%t Transpose[Select[Partition[Prime[Range[500]],2,1],PrimeQ[Times@@#- 4]&]] [[1]] (* _Harvey P. Dale_, Jan 22 2012 *)

%K nonn

%O 1,1

%A _Giovanni Teofilatto_, Apr 12 2004

%E Corrected and extended by _Harvey P. Dale_, Jan 22 2012

%E Name edited by _Robert Israel_, Jan 10 2019

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Last modified April 19 19:02 EDT 2024. Contains 371798 sequences. (Running on oeis4.)