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a(n) = Sum_{j=1..n} floor(j*sqrt(8)); n-th partial sum of Beatty sequence for sqrt(8).
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%I #11 Mar 17 2021 22:55:36

%S 2,7,15,26,40,56,75,97,122,150,181,214,250,289,331,376,424,474,527,

%T 583,642,704,769,836,906,979,1055,1134,1216,1300,1387,1477,1570,1666,

%U 1764,1865,1969,2076,2186,2299,2414,2532,2653,2777,2904,3034,3166

%N a(n) = Sum_{j=1..n} floor(j*sqrt(8)); n-th partial sum of Beatty sequence for sqrt(8).

%t c[n_] := Sum[Floor[j*Sqrt[8]], {j, 1, n}];

%t c = Table[c[n], {n, 1, 90}]

%o (Python)

%o from sympy import integer_nthroot

%o def A194112(n): return sum(integer_nthroot(8*j**2,2)[0] for j in range(1,n+1)) # _Chai Wah Wu_, Mar 17 2021

%Y Cf. A022842 (Beatty sequence for sqrt(8)).

%K nonn

%O 1,1

%A _Clark Kimberling_, Aug 16 2011