A039281 - OEIS

%I #14 Jun 28 2021 04:36:13

%S 7,13,19,27,28,30,39,45,49,52,54,57,67,75,76,78,95,99,107,108,110,112,

%T 114,119,120,122,125,135,141,147,155,156,158,167,173,177,180,182,185,

%U 193,196,198,201,208,210,215,216,218,221,225,228,230,233,245,259,267

%N Numbers whose base-4 representation has the same nonzero number of 1's and 3's.

%t Select[Range[300],DigitCount[#,4,1]==DigitCount[#,4,3]>0&] (* _Harvey P. Dale_, Apr 24 2019 *)

%Y Cf. A007090.

%K nonn,base,easy

%O 1,1

%A _Olivier Gérard_