A166447 a(n) = n*round(sqrt(n)).

0, 1, 2, 6, 8, 10, 12, 21, 24, 27, 30, 33, 36, 52, 56, 60, 64, 68, 72, 76, 80, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 186, 192, 198, 204, 210, 216, 222, 228, 234, 240, 246, 252, 301, 308, 315, 322, 329, 336, 343, 350, 357, 364, 371, 378, 385, 392, 456

Offset: 0

Author

Vladimir Joseph Stephan Orlovsky, Oct 13 2009

Keywords

• nonn
• easy

Links

• G. C. Greubel, Table of n, a(n) for n = 0..999 [Offset shifted by _Georg Fischer_, Aug 30 2021]

Programs

Magma

[n*Round(Sqrt(n)): n in [0..60]]; // Vincenzo Librandi, May 15 2016

Maple

seq(n*round(sqrt(n)), n=0..60); # Georg Fischer, Aug 28 2021
# second Maple program:
a:= n-> n*isqrt(n):
seq(a(n), n=0..60);  # Alois P. Heinz, Aug 29 2021

Mathematica

Table[n Round[Sqrt[n]],{n,0,60}] (* Harvey P. Dale, Oct 30 2021 *)

Python

from math import isqrt
def A166447(n): return n*((m:=isqrt(n))+int(n-m*(m+1)>=1)) # Chai Wah Wu, Jun 19 2024

Formula

a(n) = n*A000194(n). - R. J. Mathar, Nov 18 2009

Extensions

Offset corrected by Georg Fischer, Aug 28 2021