This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A065880 #18 May 06 2016 14:26:12
%S A065880 0,1,2,6,4,10,12,21,8,18,20,55,24,0,42,60,16,34,36,0,40,126,110,115,
%T A065880 48,0,0,108,84,116,120,155,32,66,68,0,72,222,0,156,80,246,252,172,220,
%U A065880 180,230,0,96,0,0,204,0,318,216,0,168,285,232,295,240,366,310,378,64,130
%N A065880 Largest positive number that is n times the number of 1's in its binary expansion, or 0 if no such number exists.
%C A065880 a(n) is bounded above by n*A272756(n), so a program only has to check values up to that point to see if a(n) is zero. - _Peter Kagey_, May 05 2016
%H A065880 Peter Kagey, <a href="/A065880/b065880.txt">Table of n, a(n) for n = 0..10000</a>
%e A065880 a(23)=115 since 115 is written in binary as 1110011 and 115/(1+1+1+0+0+1+1)=23 and there is no higher possibility (if k is more than 127 then k divided by its number of binary 1's is more than 26).
%t A065880 Table[SelectFirst[Reverse@ Range@ #, First@ DigitCount[#, 2] == #/n &] &[n SelectFirst[Range[2^12], # > IntegerLength[n #, 2] &]], {n, 80}] /. k_ /; MissingQ@ k -> 0 (* _Michael De Vlieger_, May 05 2016, Version 10.2 *)
%Y A065880 A052489 is the base 10 equivalent.
%Y A065880 Cf. A000120, A049445, A058898, A065413, A065878, A065879, A272756.
%K A065880 base,nonn
%O A065880 0,3
%A A065880 _Henry Bottomley_, Nov 26 2001