

A168354


Squarefree semiprimes whose binary expansion is palindromic.


1



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
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OFFSET

1,1


LINKS



EXAMPLE

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


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


CROSSREFS



KEYWORD

nonn,base


AUTHOR



STATUS

approved



