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Numbers m such that Sum_{k=1..m} (<1/2 + k*r> - <k*r>) < 0, where r=sqrt(11) and < > denotes fractional part.
4

%I #10 Feb 15 2021 02:20:59

%S 3,5,6,7,8,9,10,11,12,13,15,25,27,28,29,31,47,49,50,51,53,63,65,66,67,

%T 68,69,70,71,72,73,75,85,87,88,89,91,107,109,110,111,113,123,125,126,

%U 127,128,129,130,131,132,133,135,145,147,148,149,151,167,169,170

%N Numbers m such that Sum_{k=1..m} (<1/2 + k*r> - <k*r>) < 0, where r=sqrt(11) and < > denotes fractional part.

%C See A194368.

%t r = Sqrt[11]; c = 1/2;

%t x[n_] := Sum[FractionalPart[k*r], {k, 1, n}]

%t y[n_] := Sum[FractionalPart[c + k*r], {k, 1, n}]

%t t1 = Table[If[y[n] < x[n], 1, 0], {n, 1, 200}];

%t Flatten[Position[t1, 1]] (* A194387 *)

%t t2 = Table[If[y[n] == x[n], 1, 0], {n, 1, 200}];

%t Flatten[Position[t2, 1]] (* A194388 *)

%t t3 = Table[If[y[n] > x[n], 1, 0], {n, 1, 200}];

%t Flatten[Position[t3, 1]] (* A194389 *)

%Y Cf. A010468, A194368, A194388, A194389.

%K nonn

%O 1,1

%A _Clark Kimberling_, Aug 23 2011