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Numbers m such that Sum_{k=1..m} (<1/3 + k*r> - <k*r>) < 0, where r=sqrt(5) and < > denotes fractional part.
4

%I #8 Feb 14 2021 21:39:58

%S 4,5,8,59,76,77,80,131,148,149,152,203,220,221,224,275,292,293,296,

%T 686,758,830,902,974,991,992,995

%N Numbers m such that Sum_{k=1..m} (<1/3 + k*r> - <k*r>) < 0, where r=sqrt(5) and < > denotes fractional part.

%C See A194368.

%t r = Sqrt[5]; c = 1/3;

%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, 1000}];

%t Flatten[Position[t1, 1]] (* A194419 *)

%t t2 = Table[If[y[n] == x[n], 1, 0], {n, 1, 700}];

%t Flatten[Position[t2, 1]] (* A194420 *)

%t t3 = Table[If[y[n] > x[n], 1, 0], {n, 1, 100}];

%t Flatten[Position[t3, 1]] (* A194421 *)

%Y Cf. A194368.

%K nonn

%O 1,1

%A _Clark Kimberling_, Aug 24 2011