A057887 Number of 4-tuples of integers with GCD=1 and giving the lengths of sides of a nondegenerate quadrilateral with perimeter n.

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

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: A301806 A066847 A370121 * A202116 A215914 A006049

Adjacent sequences: A057884 A057885 A057886 * A057888 A057889 A057890

Keyword

nonn

Author

John W. Layman, Sep 19 2000

Status

approved