OFFSET

1,2

FORMULA

EXAMPLE

a(10) = 7; There are 7 numbers less than or equal to 10 that are either squarefree, a divisor of 10, or both. The numbers are 1,2,3,5,6,7,10.

MATHEMATICA

Module[{nn=80, sf}, sf=Select[Range[nn], SquareFreeQ[#]&]; Table[Length[Union[Select[sf, #<= n&], Divisors[n]]], {n, nn}]] (* Harvey P. Dale, Jul 03 2023 *)

CROSSREFS

KEYWORD

nonn

AUTHOR

Wesley Ivan Hurt, Feb 12 2022

STATUS

approved