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A240395
Number of 3 X n 0..3 arrays with no element equal to zero plus the sum of elements to its left or one plus the sum of the elements above it or two plus the sum of the elements diagonally to its northwest, modulo 4.
1
2, 12, 32, 62, 118, 206, 351, 568, 882, 1322, 1921, 2716, 3748, 5062, 6707, 8736, 11206, 14178, 17717, 21892, 26776, 32446, 38983, 46472, 55002, 64666, 75561, 87788, 101452, 116662, 133531, 152176, 172718, 195282, 219997, 246996, 276416, 308398
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = (1/6)*n^4 - (5/6)*n^3 + (13/3)*n^2 + (31/3)*n - 48 for n>5.
Conjectures from Colin Barker, Oct 27 2018: (Start)
G.f.: x*(2 + 2*x - 8*x^2 + 2*x^3 + 18*x^4 - 26*x^5 + 29*x^6 - 29*x^7 + 20*x^8 - 6*x^9) / (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>10.
(End)
EXAMPLE
Some solutions for n=4:
..3..0..0..0....3..0..0..0....3..0..0..0....3..0..0..0....3..0..0..0
..1..3..3..0....1..0..0..0....1..0..0..3....1..0..3..3....1..0..3..3
..3..1..3..2....3..0..2..3....3..0..0..1....3..2..3..2....3..0..2..2
CROSSREFS
Row 3 of A240394.
Sequence in context: A254962 A139323 A225525 * A009331 A154252 A013198
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 04 2014
STATUS
approved