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A082540 Number of ordered quadruples (a,b,c,d) with gcd(a,b,c,d)=1 (1<= {a,b,c,d} <= n.). 1
1, 15, 79, 239, 607, 1199, 2303, 3823, 6223, 9279, 13919, 19183, 27007, 35743, 47519, 60735, 78719, 97103, 122447, 148527, 181839, 216959, 262543, 306863, 365343, 423855, 495855, 569055, 661679, 748527, 862047, 972191, 1104831, 1237247 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..34.

FORMULA

a(n)=sum(k=1, n, mu(k)*floor(n/k)^4); a(n) is asymptotic to c*n^4 with c=0.92393....

PROG

(PARI) a(n)=sum(k=1, n, moebius(k)*floor(n/k)^4)

CROSSREFS

Cf. A018805 (pairs), A071778 (triples).

Sequence in context: A044583 A212746 A212741 * A269657 A189922 A085808

Adjacent sequences:  A082537 A082538 A082539 * A082541 A082542 A082543

KEYWORD

nonn

AUTHOR

Benoit Cloitre, May 11 2003

STATUS

approved

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Last modified February 16 15:55 EST 2020. Contains 331961 sequences. (Running on oeis4.)