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%I #10 Mar 28 2022 07:40:21
%S 9,11,13,15,18,22,26,30,36,44,52,60,72,88,104,120,144,176,208,240,288,
%T 352,416,480,576,704,832,960,1152,1408,1664,1920,2304,2816,3328,3840,
%U 4608,5632,6656,7680,9216,11264,13312,15360,18432,22528,26624
%N Numbers whose binary expansion is 1xy100...0 where x,y = 0 or 1.
%H Amiram Eldar, <a href="/A123760/b123760.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = 2*a(n-4) for n > 4.
%F A093873(a(n)) = 3.
%F Sum_{n>=1} 1/a(n) = 4448/6435. - _Amiram Eldar_, Mar 28 2022
%t Union[Join @@ (Table[FromDigits[Join[#, Table[0, {n}]], 2], {n, 0, 11}] & /@ {{1, 0, 0, 1}, {1, 0, 1, 1}, {1, 1, 0, 1}, {1, 1, 1, 1}})] (* _Amiram Eldar_, Mar 28 2022 *)
%Y Cf. A029744, A070875, A070876, A093873.
%K nonn,base
%O 1,1
%A _Reinhard Zumkeller_, Oct 13 2006
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