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 A143116 #13 Aug 16 2025 23:59:19
%S A143116 2,4,18,16,65,132,518,256,1026,2050,4224,8196,16640,65548,262155,
%T A143116 65536,262208,524304,1050624,2097160,8388618,8388864,33554562,
%U A143116 33554448,67174400,134218240,268435458,1073741844,1073807360,8589934620
%N A143116 a(n) = the smallest positive multiple of n that has exactly n (nonleading) 0's in its binary representation.
%H A143116 Ray Chandler, <a href="/A143116/b143116.txt">Table of n, a(n) for n = 1..2046</a>
%e A143116 For n = 3, checking: 3*1=3 (11 in binary, zero 0's). 3*2=6 (110 in binary, one 0). 3*3=9 (1001 in binary, two 0's). 3*4=12 (1100 in binary, two 0's). 3*5=15 (1111 in binary, zero 0's). 3*6=18 (10010 in binary, three 0's). So a(3) = 18.
%t A143116 a[n_]:=Module[{m=1},Until[DigitCount[n*m,2][[2]]==n,m++];n*m];Array[a,20] (* _James C. McMahon_, Aug 16 2025 *)
%Y A143116 Cf. A143115.
%K A143116 base,nonn
%O A143116 1,1
%A A143116 _Leroy Quet_, Jul 25 2008
%E A143116 a(6)-a(27) from _Owen Whitby_, Oct 22 2008
%E A143116 a(28)-a(30) from _Ray Chandler_, Nov 11 2008