%I #13 May 21 2023 12:26:53
%S 1535,1919,2015,2039,2045,3455,3551,3575,3581,3935,3959,3965,4055,
%T 4061,4085,4607,4991,5087,5111,5117,5375,5887,5951,6079,6095,6127,
%U 6131,6139,6140,6142,6655,7039,7135,7159,7165,7295
%N Numbers whose base-4 representation contains exactly two 1's and four 3's.
%t Select[Range[8000],DigitCount[#,4,1]==2&&DigitCount[#,4,3]==4&] (* _Harvey P. Dale_, Jan 31 2015 *)
%Y Cf. A007090.
%K nonn,base
%O 1,1
%A _Clark Kimberling_