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A334707
Number of non-collinear triples in a 5 X n rectangular grid.
2
0, 100, 412, 1056, 2148, 3820, 6176, 9352, 13456, 18612, 24940, 32568, 41596, 52164, 64384, 78376, 94256, 112156, 132180, 154464, 179116, 206260, 236016, 268512, 303848, 342164, 383572, 428192, 476140, 527548, 582520, 641192, 703672, 770084, 840548, 915192, 994116
OFFSET
1,2
FORMULA
From Stefano Spezia, Jun 20 2020: (Start)
G.f.: 4*x*(25 + 53*x + 83*x^2 + 87*x^3 + 67*x^4 + 35*x^5 + 10*x^6)/((1 - x)^4*(1 + 2*x + 3*x^2 + 3*x^3 + 2*x^4 + x^5)).
a(n) = 2*a(n-1) - a(n-2) + a(n-3) - a(n-4) - a(n-5) + a(n-6) - a(n-7) + 2*a(n-8) - a(n-9) for n > 9. (End)
CROSSREFS
A row of A334705.
Sequence in context: A250853 A017270 A105089 * A017510 A290654 A017642
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 13 2020
EXTENSIONS
Terms a(6) and beyond from Giovanni Resta, Jun 20 2020
STATUS
approved