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Numbers with a single 0 in their base 4 expansion.
2

%I #12 Oct 04 2018 10:43:16

%S 0,4,8,12,17,18,19,20,24,28,33,34,35,36,40,44,49,50,51,52,56,60,69,70,

%T 71,73,74,75,77,78,79,81,82,83,84,88,92,97,98,99,100,104,108,113,114,

%U 115,116,120,124,133,134,135,137,138,139,141

%N Numbers with a single 0 in their base 4 expansion.

%C Each member of the sequence is either 4*a+b for a in the sequence and b in {1,2,3}, or 4*a for a in A023705. - _Robert Israel_, Oct 04 2018

%H Robert Israel, <a href="/A023706/b023706.txt">Table of n, a(n) for n = 1..10000</a>

%p R23705:= {1,2,3}:

%p R:= {}: A:= 0;

%p for i from 1 to 4 do

%p R:= map(t ->4*t, R23705) union map(t -> (4*t+1,4*t+2,4*t+3), R);

%p R23705:= map(t -> (4*t+1,4*t+2,4*t+3), R23705);

%p A:= A, op(sort(convert(R,list)));

%p od:

%p A; # _Robert Israel_, Oct 04 2018

%t Select[ Range[ 0, 160 ], (Count[ IntegerDigits[ #, 4 ], 0 ]==1)& ]

%o (PARI) isok(n) = (n==0) || (#select(x->(x==0), digits(n, 4)) == 1); \\ _Michel Marcus_, Oct 04 2018

%Y Cf. A023705.

%K nonn,base,easy

%O 1,2

%A _Olivier GĂ©rard_