OFFSET
0,2
COMMENTS
a(n) is the number of integers k <= 10^n with mu(k)=1 where mu(k) is the Möbius function.
EXAMPLE
a(1) = 3 because there are 3 squarefree integers with an even number of prime factors <= 10: 1, 6, 10.
MATHEMATICA
Table[Length@Select[Range[10^n], MoebiusMu@#==1&], {n, 0, 6}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Giorgos Kalogeropoulos, Oct 30 2021
STATUS
approved