A180816 - OEIS

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A180816

Number of distinct solutions of sum{i=1..4}(x(2i-1)*x(2i)) = 0 (mod n), with x() only in 2..n-2

0, 0, 0, 1, 3, 30, 102, 485, 1209, 3622, 7472, 18761, 32668, 68364, 113299, 211048, 315291, 560656, 783765, 1302666, 1793022, 2758386, 3624837, 5631414, 7012350, 10247902, 13024865, 18346867, 22183836, 31716850, 37062779, 51151518, 61104631

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,5

COMMENTS

Column 4 of A180823

LINKS

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

EXAMPLE

Solutions for sum of products of 4 2..4 pairs = 0 (mod 6) are

(2*2 + 2*2 + 2*2 + 2*3) (2*2 + 2*2 + 2*2 + 3*4) (2*2 + 2*2 + 2*3 + 4*4)

(2*2 + 2*2 + 2*4 + 2*4) (2*2 + 2*2 + 3*4 + 4*4) (2*2 + 2*3 + 2*3 + 2*4)

(2*2 + 2*3 + 2*4 + 3*4) (2*2 + 2*3 + 4*4 + 4*4) (2*2 + 2*4 + 2*4 + 4*4)

(2*2 + 2*4 + 3*3 + 3*3) (2*2 + 2*4 + 3*4 + 3*4) (2*2 + 3*4 + 4*4 + 4*4)

(2*3 + 2*3 + 2*3 + 2*3) (2*3 + 2*3 + 2*3 + 3*4) (2*3 + 2*3 + 2*4 + 4*4)

(2*3 + 2*3 + 3*3 + 3*3) (2*3 + 2*3 + 3*4 + 3*4) (2*3 + 2*4 + 2*4 + 2*4)

(2*3 + 2*4 + 3*4 + 4*4) (2*3 + 3*3 + 3*3 + 3*4) (2*3 + 3*4 + 3*4 + 3*4)

(2*3 + 4*4 + 4*4 + 4*4) (2*4 + 2*4 + 2*4 + 3*4) (2*4 + 2*4 + 4*4 + 4*4)

(2*4 + 3*3 + 3*3 + 4*4) (2*4 + 3*4 + 3*4 + 4*4) (3*3 + 3*3 + 3*3 + 3*3)

(3*3 + 3*3 + 3*4 + 3*4) (3*4 + 3*4 + 3*4 + 3*4) (3*4 + 4*4 + 4*4 + 4*4)

CROSSREFS

Sequence in context: A152767 A195029 A211617 * A308402 A035328 A100259

Adjacent sequences: A180813 A180814 A180815 * A180817 A180818 A180819

KEYWORD

nonn

AUTHOR

R. H. Hardin Sep 20 2010

STATUS

approved