%I #5 Jul 29 2015 09:47:12
%S 0,21,364,4833,58360,676941,7731364,88086873,1008580720,11652595461
%N Number of collinear point 5-tuples in a 7 X 7 X 7 X ... n-dimensional cubic grid
%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (40, -590, 3800, -9009) conjectured.
%F Conjecture: a(n) = 2*11^n+13^n/2+5*9^n-15*7^n/2 ; a(n) = +40*a(n-1) -590*a(n-2) +3800*a(n-3) -9009*a(n-4). G.f.: x*(21-476*x+2663*x^2) / ( (11*x-1)*(13*x-1)*(7*x-1)*(9*x-1) ). [R. J. Mathar May 25 2010]
%K nonn
%O 0,2
%A _R. H. Hardin_, suggested by R. J. Mathar in the Sequence Fans Mailing List, May 25 2010