%I
%S 7,19,31,41,43,79,89,107,137,157,197,233,263,271,293,317,367,379,433,
%T 449,479,491,499,601,641,653,673,751,757,761,769,787,797,821,823,827,
%U 853,887
%N In the decimal expansion of Pi, the first occurrence of these primes begins at a prime position.
%C We label the positions in 3.14159... so that 1 is in position 1, 4 in position 2, 1 in position 3, 5 in position 4, and so on.
%e The first 19 in the decimal expansion of Pi (see A000796) starts in position 37, which is a prime.
%t pos_in_Pi={1,6,9,2,4,7,13,11,5,49,94,148,110,1,3,....};
%t s={};Do[If[PrimeQ[x]&&PrimeQ[pos_in_Pi[[x]]],AppendTo[s,pos_in_Pi]],{x,Length[v]}];s
%Y Cf. A000796.
%K nonn,base
%O 1,1
%A _Vicente Izquierdo Gomez_, Sep 01 2012
%E Edited by _N. J. A. Sloane_, Sep 09 2012
