A179866 A057330 with duplicates omitted.

2, 1531, 16651, 15514861

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Jan 11 2011

Keywords

• nonn
• more

Examples

			2*2-1=3,2*3-1=5,2*5-1=11;
2,3,5;
1531,3061,6121,12241,24481;
16651,33301,66601,133201,266401,532801,1065601;
15514861,31029721,62059441,124118881,248237761,496475521,992951041,1985902081;
		

Crossrefs

Cf. A057330, A005382

Programs

Mathematica

q=1; Reap[Do[lst={a=Prime[n]}; While[PrimeQ[a=2a-1], AppendTo[lst,a]]; If[Length[lst]>q, q=Length[lst]; Print[lst]; Sow[lst[[1]]]], {n,10^6}]][[2,1]]

Extensions

Edited by N. J. A. Sloane, Jan 11 2011.