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a(n) = Sum_{k=1..n} [ 1/{k*sqrt(7)} ] where {x} := x - [ x ].
2

%I #17 Sep 08 2022 08:44:48

%S 1,4,5,6,10,11,12,18,19,21,30,31,33,57,58,61,62,63,66,67,68,72,73,75,

%T 81,82,84,96,97,99,153,154,157,158,159,163,164,165,170,171,173,181,

%U 182,184,201,202,204,205,206,209,210,211,215,216,217,223,224,226

%N a(n) = Sum_{k=1..n} [ 1/{k*sqrt(7)} ] where {x} := x - [ x ].

%H Clark Kimberling, <a href="/A024565/b024565.txt">Table of n, a(n) for n = 1..1000</a>

%t Table[Sum[Floor[1/FractionalPart[k*Sqrt[7]]], {k, 1, n}], {n, 100}] (* _Clark Kimberling_, Aug 15 2012 *)

%o (Magma) a:=Sqrt(7); [&+[Floor(1/(k*a-Floor(k*a))):k in [1..n]]:n in [1..60]]; // _Marius A. Burtea_, Jul 16 2019

%Y Cf. A024566. Partial sums of A024564.

%K nonn

%O 1,2

%A _Clark Kimberling_

%E Corrected by _Clark Kimberling_, Aug 15 2012