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Numbers with exactly 2 1's in their base 4 expansion.
2

%I #13 Sep 13 2023 07:25:27

%S 5,17,20,22,23,25,29,37,53,65,68,70,71,73,77,80,82,83,88,90,91,92,94,

%T 95,97,100,102,103,105,109,113,116,118,119,121,125,133,145,148,150,

%U 151,153,157,165,181,197,209,212,214,215,217

%N Numbers with exactly 2 1's in their base 4 expansion.

%H Seiichi Manyama, <a href="/A023711/b023711.txt">Table of n, a(n) for n = 1..10000</a>

%t Select[ Range[ 240 ], (Count[ IntegerDigits[ #, 4 ], 1 ]==2)& ]

%K nonn,base,easy

%O 1,1

%A _Olivier GĂ©rard_