A180787 - OEIS

A180787

Number of distinct solutions of sum{i=1..5}(x(2i-1)*x(2i)) = 1 (mod n), with x() only in 1..n-1

0, 1, 5, 64, 400, 1914, 7589, 24902, 73134, 188315, 455127, 996083, 2098908, 4080930, 7790731, 13869018, 24527424, 40768032, 67955336, 106952861, 169909977, 255608028, 390623704, 566247614, 837326375, 1175991196, 1690928973

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OFFSET

1,3

COMMENTS

Column 5 of A180793

LINKS

R. H. Hardin, Table of n, a(n) for n=1..250

EXAMPLE

Solutions for sum of products of 5 1..2 pairs = 1 (mod 3) are

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

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

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

CROSSREFS

Sequence in context: A193834 A193875 A193184 * A222455 A351855 A178295

Adjacent sequences: A180784 A180785 A180786 * A180788 A180789 A180790

KEYWORD

nonn

AUTHOR

R. H. Hardin Sep 20 2010

STATUS

approved