0,8

Table of n, a(n) for n=0..79.

From Ridouane Oudra, May 11 2019: (Start)

a(n) = (1/2)*(n + 1 - t - abs(n + 1 - t^2)), where t = floor(sqrt(n+1) + 1/2).

a(n) = (1/2)*(n + 1 - A000194(n+1) - abs(n + 1 - A000194(n+1)^2)).

a(n) = (1/2)*(A056847(n+1) - A053188(n+1)). (End)

(MAGMA) [1/2*(n+1-Floor(Sqrt(n+1)+1/2)-Abs(n+1-(Floor(Sqrt(n+1)+1/2))^2)):n in [0..90]]; // Marius A. Burtea, May 09 2019

(PARI) f(n) = sqrtint(4*n)-2*sqrtint(n); \\ A023969

a(n) = sum(k=0, n, f(k)); \\ Michel Marcus, May 10 2019

Cf. A023969.

Sequence in context: A196183 A200264 A104406 * A194225 A025782 A120506

Adjacent sequences: A080341 A080342 A080343 * A080345 A080346 A080347

nonn

N. J. A. Sloane, Mar 20 2003

approved