A339363 - OEIS

%I #17 Apr 26 2021 14:05:57

%S 0,1,1,2,3,4,4,4,6,7,8,9,9,9,9,12,13,14,15,16,16,16,16,16,20,21,22,23,

%T 24,25,25,25,25,25,25,30,31,32,33,34,35,36,36,36,36,36,36,36,42,43,44,

%U 45,46,47,48,49,49,49,49,49,49,49,49,56,57,58,59,60,61,62,63,64,64,64

%N a(n) = Sum_{k=1..floor(sqrt(n))} floor(sqrt(n-k)).

%C Contains all nonnegative integers not in A189151.

%t Table[Sum[Floor[Sqrt[n - k]], {k, Floor[Sqrt[n]]}], {n, 80}]

%o (PARI) a(n) = sum(k=1, sqrtint(n), sqrtint(n-k)); \\ _Michel Marcus_, Apr 24 2021

%o (Python)

%o from math import isqrt

%o def a(n): return sum(isqrt(n-k) for k in range(1, isqrt(n)+1))

%o print([a(n) for n in range(1, 75)]) # _Michael S. Branicky_, Apr 24 2021

%Y Cf. A189151.

%K nonn

%O 1,4

%A _Wesley Ivan Hurt_, Apr 24 2021