%I

%S 3,4,8,28,52,56,82,1472,1484,8669

%N Numbers k such that Sum_{j=1..k-1} j*2^(j-1) is prime.

%t s = 0; Do[s += (x-1)*2^(x-1)/2; If[PrimeQ[s], Print[x]], {x, 10^4}] (* _Ryan Propper_, Jan 01 2007 *)

%Y Cf. A000523.

%K more,nonn

%O 1,1

%A _Jorge Coveiro_, Jul 27 2006

%E One more term from _Ryan Propper_, Jan 01 2007

%E Name simplified by _Jon E. Schoenfield_, Sep 23 2018