A168354 Squarefree semiprimes whose binary expansion is palindromic.

15, 21, 33, 51, 65, 85, 93, 119, 129, 219, 341, 365, 381, 403, 427, 471, 511, 633, 717, 771, 843, 951, 1057, 1137, 1241, 1273, 1285, 1317, 1397, 1501, 1651, 1707, 1799, 1967, 2047, 2049, 2661, 2973, 3579, 3687, 3831, 4097, 4321, 4369, 4529, 4593, 4681

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Nov 23 2009

Keywords

• nonn
• base

Examples

			15 = 3*5 = {1,1,1,1}.
21 = 3*7 = {1,0,1,0,1}.
33 = 3*11 = {1,0,0,0,0,1}.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A016041.

Intersection of A006995 and A006881. - Michel Marcus, Nov 24 2020

Programs

Mathematica

f1[n_]:=Reverse[IntegerDigits[n,2]]==IntegerDigits[n,2]; f2[n_]:=Last/@FactorInteger[n]=={1,1}; lst={};Do[If[f1[n]&&f2[n],AppendTo[lst,n]],{n,8!}];lst