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Numbers whose base-4 representation contains exactly three 1's and two 3's.
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%I #14 May 21 2023 12:22:49

%S 351,375,381,471,477,501,855,861,885,981,1119,1143,1149,1239,1245,

%T 1269,1311,1335,1341,1359,1391,1395,1403,1404,1406,1439,1463,1469,

%U 1479,1485,1491,1499,1500,1502,1511,1517,1521,1524

%N Numbers whose base-4 representation contains exactly three 1's and two 3's.

%t Select[Range[1600],DigitCount[#,4,1]==3&&DigitCount[#,4,3]==2&] (* _Harvey P. Dale_, Jun 20 2017 *)

%Y Cf. A007090.

%K nonn,base

%O 1,1

%A _Clark Kimberling_