OFFSET
0,3
REFERENCES
M. Boll, Tables Numériques Universelles. Dunod, Paris, 1947, p. 46.
M. Hall, Jr., The Diophantine equation x^3-y^2=k, pp. 173-198 of A. O. L. Atkin and B. J. Birch, editors, Computers in Number Theory. Academic Press, NY, 1971.
A. V. Lebedev and R. M. Fedorova, A Guide to Mathematical Tables. Pergamon, Oxford, 1960, p. 17.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
T. D. Noe, Table of n, a(n) for n = 0..1000
FORMULA
a(n) = floor(n^(3/2) + 1/2). - Ridouane Oudra, Nov 13 2019
a(n) = sqrt(A077118(n)). - Chai Wah Wu, Jul 30 2022
MATHEMATICA
t[n_]:=Module[{flt=Floor[n], cet=Ceiling[n]}, If[n-flt<cet-n, flt, cet]]; t/@(Range[0, 60]^((3/2))) (* Harvey P. Dale, May 12 2011 *)
PROG
(Haskell)
a002821 = round . sqrt . fromIntegral . (^ 3)
-- Reinhard Zumkeller, Jul 11 2014
(Python)
from math import isqrt
def A002821(n): return (m:=isqrt(k:=n**3))+int((k-m*(m+1)<<2)>=1) # Chai Wah Wu, Jul 30 2022
CROSSREFS
KEYWORD
nonn,easy,nice
AUTHOR
STATUS
approved