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%I #17 Mar 31 2015 17:31:24
%S 0,1,2,4,5,6,9,10,12,17,18,19,20,21,22,24,25,26,28,35,37,38,41,42,44,
%T 49,50,52,56,67,69,70,71,73,74,75,76,77,78,81,82,83,84,85,86,88,89,90,
%U 92,97,98,99,100,101,102,104,105,106,108,112,113,114,116,120,135,139
%N Numbers whose numbers of zeros and ones in binary representation differ at most by 1.
%C A031443 is a subsequence; abs(A037861(a(n))) <= 1.
%H Reinhard Zumkeller, <a href="/A089648/b089648.txt">Table of n, a(n) for n = 1..10000</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/DigitCount.html">Digit Count</a>
%H <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>
%t Select[Range[0,7! ],Abs[DigitCount[ #,2,0]-DigitCount[ #,2,1]]<2 &] (* _Vladimir Joseph Stephan Orlovsky_, Feb 16 2010 *)
%o (Haskell)
%o a089648 n = a089648_list !! (n-1)
%o a089648_list = filter ((<= 1) . abs . a037861) [0..]
%o -- _Reinhard Zumkeller_, Mar 31 2015
%Y Cf. A023416, A000120.
%Y Cf. A037861, union of A031443, A031444 and A031448.
%K nonn,base
%O 1,3
%A _Reinhard Zumkeller_, Jan 02 2004