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A057828 Number of perfect squares, k^2, where k^2 <= n and gcd(k,n) = 1. 3
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: A191373 A322873 A026904 * A082498 A112223 A324810

Adjacent sequences:  A057825 A057826 A057827 * A057829 A057830 A057831

KEYWORD

nonn,look

AUTHOR

Leroy Quet, Nov 08 2000

STATUS

approved

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Last modified November 21 01:23 EST 2019. Contains 329348 sequences. (Running on oeis4.)