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A057887 Number of 4-tuples of integers with GCD=1 and giving the lengths of sides of a nondegenerate quadrilateral with perimeter n. 2
0, 0, 0, 1, 1, 2, 3, 4, 7, 8, 13, 13, 22, 22, 33, 33, 50, 45, 70, 65, 92, 87, 125, 111, 160, 145, 196, 184, 252, 215, 308, 278, 359, 330, 440, 385, 525, 464, 593, 546, 715, 606, 825, 735, 905, 832, 1078, 926, 1219, 1065, 1328, 1223, 1547, 1310, 1715, 1529, 1855 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

Table of n, a(n) for n=1..57.

FORMULA

Moebius transform of A057886.

EXAMPLE

There are five quadrilaterals with perimeter 8, with sides (1,1,3,3), (1,2,2,3), (1,2,3,2), (1,3,1,3) and (2,2,2,2). (2,2,2,2) is omitted since it has GCD=2, so a(8)=4.

CROSSREFS

Cf. A051493.

Sequence in context: A211659 A301806 A066847 * A202116 A215914 A006049

Adjacent sequences:  A057884 A057885 A057886 * A057888 A057889 A057890

KEYWORD

nonn

AUTHOR

John W. Layman, Sep 19 2000

STATUS

approved

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Last modified November 21 11:31 EST 2018. Contains 317447 sequences. (Running on oeis4.)