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 A087106 Primes of the form (prime(k-1)+1)*(prime(k+1)-1) + 1, k>1. 2

%I

%S 13,61,97,193,397,1597,1933,9001,12097,14821,18217,21001,31321,37633,

%T 74521,91141,96097,122497,168037,211597,266221,478801,605221,719041,

%U 760321,781453,808081,861121,915769,1034281,1245421

%N Primes of the form (prime(k-1)+1)*(prime(k+1)-1) + 1, k>1.

%H Vincenzo Librandi, <a href="/A087106/b087106.txt">Table of n, a(n) for n = 1..1000</a>

%e k=25: (prime(25-1)+1)*(prime(25+1)-1)=(89+1)*(101-1)=9000, as 9000+1=A000040(1118), 9001 is a term.

%t Select[Table[(Prime[n-1]+1)*(Prime[n+1]-1)+1,{n,0,1000}],PrimeQ] (* _Vincenzo Librandi_, Jul 15 2012 *)

%o (Magma) [p: n in [2..200] | IsPrime(p) where p is (NthPrime(n-1)+1)*(NthPrime(n+1)-1)+1]; // _Vincenzo Librandi_, Jul 16 2012

%Y Cf. A087105.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Aug 10 2003

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Last modified March 29 17:51 EDT 2023. Contains 361599 sequences. (Running on oeis4.)