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A172072 Numbers n such that either prime(n)-5/2-+7/2 is prime. 1

%I #6 Jun 13 2017 13:39:39

%S 1,5,6,7,8,9,10,12,14,15,16,17,19,21,22,24,27,28,29,30,33,37,38,40,41,

%T 45,46,50,51,52,55,56,57,59,61,65,66,68,71,72,74,75,77,85,87,90,91,97,

%U 101,103,104,106,108,109,111,112,114,118,119,120,124,130,131,134,144

%N Numbers n such that either prime(n)-5/2-+7/2 is prime.

%H Charles R Greathouse IV, <a href="/A172072/b172072.txt">Table of n, a(n) for n = 1..10000</a>

%e a(1)=1 because prime(1)-5/2-7/2=2-5/2-7/2=-4(nonprime) and prime(1)-5/2+7/2=2-5/2+7/2=3(prime).

%o (PARI) is(n,p=prime(n))=isprime(p-6) || isprime(p+1) \\ _Charles R Greathouse IV_, Jun 13 2017

%Y Cf. A000040, A046117, A172071.

%K nonn

%O 1,2

%A _Juri-Stepan Gerasimov_, Jan 25 2010

%E Corrected (57 inserted) by _R. J. Mathar_, May 02 2010

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Last modified April 24 13:58 EDT 2024. Contains 371960 sequences. (Running on oeis4.)