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%I #11 Feb 16 2021 02:08:53
%S 31261,36199,44869,49471,62521,72397,83086,138994,173311,182527,
%T 224962,259891,277987,346621,370126,415423,443746,464245,480331,
%U 519781,544006,563326,599245,693241,784681,880561,928489,980743,991237,1032937
%N The products k of two distinct primes such that 2*k-1, 4*k-3, 8*k-7, 16*k-15, 32*k-31, 64*k-63, 128*k-127 and 256*k-255 are also products of two distinct primes.
%e 31261 is a term because 31261 = 43*727, 2*31261 - 1 = 62521 = 103*607, ..., 256*31261 - 1 = 8002561 = 7*1143223, ...
%t f[n_]:=Last/@FactorInteger[n]=={1,1}; lst={};Do[If[f[n]&&f[2*n-1]&&f[4*n-3]&&f[8*n-7]&&f[16*n-15]&&f[32*n-31]&&f[64*n-63]&&f[128*n-127]&&f[256*n-255],AppendTo[lst,n]],{n,31261,5*9!}];lst
%Y Cf. A006881, A177210, A177211, A177212, A177213, A177214, A177215, A177216.
%K nonn
%O 1,1
%A _Vladimir Joseph Stephan Orlovsky_, May 04 2010
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