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A247455 Numbers k such that d(r,k) = 0 and d(s,k) = 0, where d(x,k) = k-th binary digit of x, r = {sqrt(2)}, s = {3*sqrt(2)}, and { } = fractional part. 6

%I

%S 1,8,9,10,11,15,21,25,29,38,42,48,51,54,57,58,59,62,64,66,70,72,78,81,

%T 82,86,89,93,96,107,109,111,113,122,128,130,134,136,139,144,147,148,

%U 149,151,153,161,162,165,169,173,181,182,183,187,191,195,200,202

%N Numbers k such that d(r,k) = 0 and d(s,k) = 0, where d(x,k) = k-th binary digit of x, r = {sqrt(2)}, s = {3*sqrt(2)}, and { } = fractional part.

%C Every positive integer lies in exactly one of these: A247455, A247456, A247457, A247758. Let s denote any of these; what can be said about lim(#s < n)/n, where (#s < n) represents the number of numbers in s that are < n?

%H Clark Kimberling, <a href="/A247455/b247455.txt">Table of n, a(n) for n = 1..1000</a>

%e {1*sqrt(2)} has binary digits 0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1,...

%e {3*sqrt(2)} has binary digits 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 1,...

%e so that a(1) = 2 and a(2) = 8.

%t z = 400; r = FractionalPart[Sqrt[2]]; s = FractionalPart[3*Sqrt[2]];

%t u = Flatten[{ConstantArray[0, -#[[2]]], #[[1]]}] &[RealDigits[r, 2, z]]

%t v = Flatten[{ConstantArray[0, -#[[2]]], #[[1]]}] &[RealDigits[s, 2, z]]

%t t1 = Table[If[u[[n]] == 0 && v[[n]] == 0, 1, 0], {n, 1, z}];

%t t2 = Table[If[u[[n]] == 0 && v[[n]] == 1, 1, 0], {n, 1, z}];

%t t3 = Table[If[u[[n]] == 1 && v[[n]] == 0, 1, 0], {n, 1, z}];

%t t4 = Table[If[u[[n]] == 1 && v[[n]] == 1, 1, 0], {n, 1, z}];

%t Flatten[Position[t1, 1]] (* A247455 *)

%t Flatten[Position[t2, 1]] (* A247456 *)

%t Flatten[Position[t3, 1]] (* A247457 *)

%t Flatten[Position[t4, 1]] (* A247458 *)

%Y Cf. A246356, A247456, A247457, A247458.

%K nonn,easy,base

%O 1,2

%A _Clark Kimberling_, Sep 18 2014

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Last modified January 24 16:34 EST 2020. Contains 331207 sequences. (Running on oeis4.)