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A239844
Number of n X 2 0..3 arrays with no element equal to one plus the sum of elements to its left or one plus the sum of elements above it or two plus the sum of the elements diagonally to its northwest, modulo 4.
1
3, 8, 17, 35, 64, 109, 176, 272, 405, 584, 819, 1121, 1502, 1975, 2554, 3254, 4091, 5082, 6245, 7599, 9164, 10961, 13012, 15340, 17969, 20924, 24231, 27917, 32010, 36539, 41534, 47026, 53047, 59630, 66809, 74619, 83096, 92277, 102200, 112904, 124429
OFFSET
1,1
FORMULA
Empirical: a(n) = (1/24)*n^4 + (1/12)*n^3 + (11/24)*n^2 + (53/12)*n - 6 for n>2.
Conjectures from Colin Barker, Oct 26 2018: (Start)
G.f.: x*(1 - x + x^2)*(3 - 4*x + 4*x^3 - 2*x^4) / (1 - x)^5.
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>7.
(End)
EXAMPLE
Some solutions for n=4:
..0..0....3..3....0..3....0..0....0..3....0..0....0..0....0..0....0..0....0..3
..0..0....3..2....3..3....0..0....0..3....0..0....0..3....3..3....0..0....3..3
..0..3....0..0....3..2....0..0....3..1....0..3....3..3....3..3....0..3....3..2
..3..1....0..3....0..3....0..0....3..3....3..3....3..2....0..2....0..3....0..0
CROSSREFS
Column 2 of A239849.
Sequence in context: A145071 A182734 A327608 * A182616 A159217 A052996
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 28 2014
STATUS
approved