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A174804
a(n) = n*ceiling(sqrt(n))*floor(sqrt(n)).
2
0, 1, 4, 6, 16, 30, 36, 42, 48, 81, 120, 132, 144, 156, 168, 180, 256, 340, 360, 380, 400, 420, 440, 460, 480, 625, 780, 810, 840, 870, 900, 930, 960, 990, 1020, 1050, 1296, 1554, 1596, 1638, 1680, 1722, 1764, 1806, 1848, 1890, 1932, 1974, 2016, 2401, 2800
OFFSET
0,3
COMMENTS
As a(n^2) = n^4, A000583 is a subsequence. - Bernard Schott, Feb 01 2023
FORMULA
a(n) = n*A000196(n)*A003059(n). - Michel Marcus, Feb 14 2018
MATHEMATICA
f[n_]:=n*Floor[Sqrt[n]]*Ceiling[Sqrt[n]]; Table[f[n], {n, 0, 5!}]
PROG
(PARI) a(n) = n*sqrtint(n)*ceil(sqrt(n)); \\ Michel Marcus, Feb 14 2018
(Python)
from math import isqrt
def A174804(n): return n*(n if (k:=(m:=isqrt(n))**2)==n else k+m) # Chai Wah Wu, Jul 29 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved