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Primes p such that the nearest integer to p * K is prime, where K is Catalan's constant.
2

%I #10 Jun 15 2013 01:51:42

%S 2,3,5,19,47,67,73,97,139,163,211,263,281,307,379,401,433,457,479,499,

%T 503,523,569,571,641,647,719,739,811,859,883,1187,1193,1259,1289,1409,

%U 1423,1427,1499,1571,1619,1637,1663,1787,1879,1901,1907,1951,1999,2089

%N Primes p such that the nearest integer to p * K is prime, where K is Catalan's constant.

%H Vincenzo Librandi, <a href="/A118625/b118625.txt">Table of n, a(n) for n = 1..1000</a>

%t lst={};Do[p=Prime[n];If[PrimeQ[Round[p*Catalan]],AppendTo[lst,p]],{n,10^3}];lst

%K nonn,easy

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, Aug 25 2008

%E Edited by _Charles R Greathouse IV_, Nov 11 2009

%E Typo in Mma program corrected by _Vincenzo Librandi_, Jun 15 2013