OFFSET
1,2
LINKS
Jason Kimberley, Table of n, a(n) for n = 1..5000
FORMULA
a(n) = A013928(n^2).
a(n) ~ 6*n^2/Pi^2 + O(n). - Amiram Eldar, Mar 09 2021
MATHEMATICA
Table[Count[Range[n^2], k_ /; SquareFreeQ@ k], {n, 53}] (* Michael De Vlieger, Nov 24 2016 *)
Module[{nn=60, sf}, sf=Accumulate[Table[If[SquareFreeQ[n], 1, 0], {n, 0, nn^2}]]; Table[sf[[k^2]], {k, nn}]] (* Harvey P. Dale, Nov 14 2020 *)
PROG
(Magma)
A278100:=func<n|#[k:k in[1..n^2-1]|IsSquarefree(k)]>;
[A278100(n):n in[1..53]]; // in cubic time
(PARI) a(n) = #select(x->issquarefree(x), vector(n^2-1, k, k)); \\ Michel Marcus, Nov 12 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jason Kimberley, Nov 12 2016
STATUS
approved