A178351 Number of collinear point 5-tuples in a 7 X 7 X 7 X ... n-dimensional cubic grid

0, 21, 364, 4833, 58360, 676941, 7731364, 88086873, 1008580720, 11652595461

Offset

0,2

Links

Table of n, a(n) for n=0..9.

Index entries for linear recurrences with constant coefficients, signature (40, -590, 3800, -9009) conjectured.

Formula

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]

Crossrefs

Sequence in context: A302876 A303524 A108495 * A324360 A323001 A152182

Adjacent sequences: A178348 A178349 A178350 * A178352 A178353 A178354

Keyword

nonn

Author

R. H. Hardin, suggested by R. J. Mathar in the Sequence Fans Mailing List, May 25 2010

Status

approved