%I #12 May 21 2023 12:25:25
%S 1375,1399,1405,1495,1501,1525,1879,1885,1909,2005,3415,3421,3445,
%T 3541,3925,4447,4471,4477,4567,4573,4597,4951,4957,4981,5077,5215,
%U 5239,5245,5335,5341,5365,5407,5431,5437,5455,5487
%N Numbers whose base-4 representation contains exactly four 1's and two 3's.
%Y Cf. A007090.
%K nonn,base
%O 1,1
%A _Clark Kimberling_