%I #19 Apr 11 2021 04:52:15
%S 1,4,7,16,19,21,22,25,26,28,31,64,67,69,70,73,74,76,79,81,82,84,87,88,
%T 91,93,94,97,98,100,103,104,107,109,110,112,115,117,118,121,122,124,
%U 127,256,259,261,262,265,266,268,271,273,274,276,279,280,283,285,286
%N Numbers that have an even number of 0's and an odd number of 1's in binary expansion.
%H Indranil Ghosh, <a href="/A059014/b059014.txt">Table of n, a(n) for n = 1..50000</a> (terms 1..1000 from Harvey P. Dale)
%e 21 is in the sequence because 21 = 10101_2. '10101' has two 0's and three 1's. - _Indranil Ghosh_, Feb 06 2017
%t en0on1Q[n_]:=Module[{idn2=IntegerDigits[n,2]},EvenQ[Count[idn2,0]] && OddQ[Count[idn2,1]]]; Select[Range[300],en0on1Q] (* _Harvey P. Dale_, Nov 08 2013 *)
%o (PARI) is(n)=hammingweight(n)%2 && hammingweight(bitneg(n, #binary(n)))%2==0 \\ _Charles R Greathouse IV_, Mar 26 2013
%o (Python)
%o i=1
%o j=1
%o while j<=100:
%o if not bin(i)[2:].count("0")%2 and bin(i)[2:].count("1")%2:
%o print(str(j)+" "+str(i))
%o j+=1
%o i+=1 # _Indranil Ghosh_, Feb 06 2017
%Y Cf. A000069, A001969, A059009-A059013.
%K nonn,easy
%O 1,2
%A _Patrick De Geest_, Dec 15 2000