%I A140451
%S A140451 1,3,21,105,4305,21525,5316675,3291021825,38046409656325181475
%N A140451 a(1) = 1. a(n) = the smallest positive multiple of a(n-1) with exactly 
               n 1's in its binary representation.
%C A140451 First 8 terms calculated by Richard Mathar and Jack Brennen.
%C A140451 Each term is odd.
%C A140451 Can it be proved that there always is a positive multiple of each a(n-1) 
               that has exactly n binary 1's? Or is the {a(k)} sequence finite?
%C A140451 a(10) <= 1 + 2^100 + 2^236 + 2^238 + 2^341 + 2^542 + 2^566 + 2^568 + 
               2^674 + 2^723.
%C A140451 = 441252181048159767719627961769263015304713273001222391692260944948404967249\
%C A140451 52505691843697819270690248905739332527064430387464361936830982164199090227218\
%C A140451 467520354158302900132818171857506562986336159915978303038159847425. - 
               Max Alekseyev, Oct 12 2008
%H A140451 Leroy Quet, <a href="http://www.prism-of-spirals.net/">Home Page</a> 
               (listed in lieu of email address)
%Y A140451 Sequence in context: A134057 A128281 A034268 this_sequence A054147 A043012 
               A122120
%Y A140451 Adjacent sequences: A140448 A140449 A140450 this_sequence A140452 A140453 
               A140454
%K A140451 base,more,nonn
%O A140451 1,2
%A A140451 Leroy Quet Jul 21 2008
%E A140451 a(9) from Max Alekseyev, Jul 22 2008