

A057828


Number of perfect squares, k^2, where k^2 <= n and gcd(k,n) = 1.


2



1, 1, 1, 1, 2, 1, 2, 1, 2, 2, 3, 1, 3, 2, 2, 2, 4, 1, 4, 2, 3, 2, 4, 1, 4, 3, 4, 3, 5, 1, 5, 3, 4, 3, 4, 2, 6, 3, 4, 2, 6, 2, 6, 3, 3, 3, 6, 2, 6, 3, 5, 4, 7, 3, 6, 3, 5, 4, 7, 2, 7, 4, 4, 4, 7, 3, 8, 4, 6, 2, 8, 3, 8, 4, 5, 4, 7, 3, 8, 3, 6, 5, 9, 2, 8, 5, 6, 5, 9, 2, 8, 5, 6, 5, 8, 3, 9, 4, 6, 4, 10, 3, 10, 5
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,5


COMMENTS

Number of square totatives of n, i.e., number of perfect squares less than n that are coprime to n.  Michael De Vlieger, Dec 11 2017


LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Totative.


EXAMPLE

Only 2 squares, 1 and 9, are <= 14 and relatively prime to 14. So a(14) = 2.


MATHEMATICA

Table[Count[Range[Sqrt@ n]^2, _?(CoprimeQ[#, n] &)], {n, 104}]


PROG

(Haskell)
a057828 x = length $ filter ((== 1) . (gcd x)) $
takeWhile (<= x) $ tail a000290_list
 Reinhard Zumkeller, Jul 22 2012


CROSSREFS

Cf. A000290, A010051.
Sequence in context: A287820 A191373 A026904 * A082498 A112223 A178771
Adjacent sequences: A057825 A057826 A057827 * A057829 A057830 A057831


KEYWORD

nonn,look


AUTHOR

Leroy Quet, Nov 08 2000


STATUS

approved



