A180786 - OEIS

A180786

Number of distinct solutions of sum{i=1..4}(x(2i-1)*x(2i)) = 1 (mod n), with x() only in 1..n-1

0, 0, 7, 30, 142, 502, 1519, 3828, 9145, 18966, 38562, 70202, 127954, 211261, 357465, 549988, 875942, 1273587, 1941522, 2705012, 3966472, 5325916, 7599591, 9892052, 13772034, 17476435, 23770735, 29625591, 39617904, 48129046, 63654183, 76396024

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OFFSET

1,3

COMMENTS

Column 4 of A180793

LINKS

R. H. Hardin, Table of n, a(n) for n=1..376

EXAMPLE

Solutions for sum of products of 4 1..2 pairs = 1 (mod 3) are

(1*1 + 1*1 + 1*1 + 1*1) (1*1 + 1*1 + 1*1 + 2*2) (1*1 + 1*1 + 2*2 + 2*2)

(1*1 + 1*2 + 1*2 + 1*2) (1*1 + 2*2 + 2*2 + 2*2) (1*2 + 1*2 + 1*2 + 2*2)

(2*2 + 2*2 + 2*2 + 2*2)

CROSSREFS

Sequence in context: A375308 A256981 A323929 * A343755 A026653 A271554

Adjacent sequences: A180783 A180784 A180785 * A180787 A180788 A180789

KEYWORD

nonn

AUTHOR

R. H. Hardin Sep 20 2010

STATUS

approved