%I #6 Feb 11 2014 19:05:33

%S 5,6,7,18,21,25,26,40,41,42,49,61,62,69,70,83,91,103,104,105,110,113,

%T 127,131,132,145,148,154,167,169,174,188,189,190,196,197,210,231,237,

%U 252,258,259,272,274,279,280,294,315,323,336,339,344,357,364,365,379

%N Numbers n such that floor(2*Pi*n) is prime.

%C This sequence gives the radii of circles of positive integer radius which have the integer parts of their circumferences prime.

%t Select[Range[10^3], PrimeQ[Round[2 Pi # ]] &]

%K easy,nonn

%O 1,1

%A _Joseph L. Pe_, Dec 17 2002