%I #16 Aug 13 2024 15:47:51
%S 1531,2131,2311,3061,6211,6841,7411,10321,13681,15391,16651,18121,
%T 22531,23011,24391,29671,30781,31771,33301,35311,41491,44371,46411,
%U 54601,56311,57991,60331,61381,66601,67651,78031,83431,85381,88741
%N First member of a prime quadruple in a 2p-1 progression.
%C Numbers n such that n remains prime through 3 iterations of function f(x) = 2x - 1.
%H Harvey P. Dale, <a href="/A057327/b057327.txt">Table of n, a(n) for n = 1..1000</a>
%H <a href="/index/Pri#primes_AP">Index entries for sequences related to primes in arithmetic progressions</a>
%e Quadruplets are (1531,3061,6121,12241), (2131,4261,8521,17041), ...
%t Select[Prime[Range[9000]],And@@PrimeQ[NestList[2#-1&,#,3]]&] (* _Harvey P. Dale_, May 27 2012 *)
%Y Cf. (A005382 and A005383), A057326, A057328, A057329, A057330, A005603.
%K nonn
%O 1,1
%A _Patrick De Geest_, Aug 15 2000
%E Offset changed by _Andrew Howroyd_, Aug 13 2024