%I #8 Nov 24 2021 19:16:32
%S 1,3,7,15,31,63,127,511,1023,4095,8191,131071,524287,2097151,4194303,
%T 8388607,33554431,67108863,8589934591
%N Numbers that are both lucky numbers (A000959) and of form 2^k-1 (A000225).
%C a(20) >= 17179869183 = 2^34 - 1, if it exists. - _Kevin P. Thompson_, Nov 24 2021
%e a(7) = 127 since A000959(27) = A000225(7) = 127 and it is the 7th such number with this property.
%Y Cf. A000959, A000225.
%K nonn,more
%O 1,2
%A _Naohiro Nomoto_, Oct 09 2000
%E More terms from Mark Weston (mweston(AT)uvic.ca), Oct 16 2001
%E a(18) from _Giovanni Resta_, May 10 2020
%E a(19) from _Kevin P. Thompson_, Nov 24 2021