A180819 Number of distinct solutions of sum{i=1..7}(x(2i-1)*x(2i)) = 0 (mod n), with x() only in 2..n-2

0, 0, 0, 1, 9, 168, 1636, 16029, 98932, 566139, 2452576, 9997696, 33559251, 107928162, 302208130, 819882076, 1997861697, 4777963921, 10461759204, 22651681426, 45635928642, 91229866983, 171539771236, 322071749769

Offset

1,5

Comments

Column 7 of A180823

Links

R. H. Hardin, Table of n, a(n) for n=1..183

Example

Solutions for sum of products of 7 2..3 pairs = 0 (mod 5) are
(2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*3)
(2*2 + 2*2 + 2*2 + 2*2 + 2*2 + 2*3 + 3*3)
(2*2 + 2*2 + 2*2 + 2*2 + 2*3 + 3*3 + 3*3)
(2*2 + 2*2 + 2*2 + 2*3 + 3*3 + 3*3 + 3*3)
(2*2 + 2*2 + 2*3 + 3*3 + 3*3 + 3*3 + 3*3)
(2*2 + 2*3 + 2*3 + 2*3 + 2*3 + 2*3 + 2*3)
(2*2 + 2*3 + 3*3 + 3*3 + 3*3 + 3*3 + 3*3)
(2*3 + 2*3 + 2*3 + 2*3 + 2*3 + 2*3 + 3*3)
(2*3 + 3*3 + 3*3 + 3*3 + 3*3 + 3*3 + 3*3)

Crossrefs

Sequence in context: A361094 A367135 A367139 * A132874 A223289 A281996

Adjacent sequences: A180816 A180817 A180818 * A180820 A180821 A180822

Keyword

nonn

Author

R. H. Hardin Sep 20 2010

Status

approved