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 A087394 Prime(prime(n)) when prime(prime(n)) and n are twin primes. 1

%I

%S 11,31,59,179,599,1063,1153,1787,2381,4091,4273,5869,6661,9461,9859,

%T 14867,15641,17987,20773,20899,27689,30557,39239,43651,43889,61979,

%U 63391,66749,66851,68821,84347,96797,104471,111271,132949,146989,157771

%N Prime(prime(n)) when prime(prime(n)) and n are twin primes.

%H Harvey P. Dale, <a href="/A087394/b087394.txt">Table of n, a(n) for n = 3..1000</a>

%e prime(103) = 563. prime(563) = 4091. 103 and 4091 are twin primes.

%t Select[Prime[Prime[#]]&/@Union[Flatten[Select[Partition[Prime[Range[400]],2,1], #[[2]] - #[[1]]==2&]]],AnyTrue[#+{2,-2},PrimeQ]&] (* The program uses the AnyTrue function from Mathematica version 10 *) (* _Harvey P. Dale_, Mar 21 2015 *)

%o (PARI) twips(n) = { c1=0; c2=0; forprime(x=3,n, if(isprime(x+2),c1++); x1=prime(prime(x)); if(isprime(x-2) || isprime(x+2), if(isprime(x1-2) || isprime(x1+2), print1(x1","); c2++; ) ) ); print(); print(c2/c1+.0) }

%K easy,nonn

%O 3,1

%A _Cino Hilliard_, Oct 21 2003

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Last modified December 2 14:54 EST 2022. Contains 358510 sequences. (Running on oeis4.)