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A240789 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 zero plus the sum of the elements diagonally to its northwest or zero plus the sum of the elements antidiagonally to its northeast, modulo 4. 1
3, 4, 5, 10, 13, 14, 30, 32, 36, 67, 79, 97, 173, 191, 232, 402, 464, 580, 960, 1104, 1400, 2250, 2637, 3388, 5280, 6255, 8117, 12342, 14819, 19374, 28826, 35008, 46021, 67233, 82554, 108956, 156715, 194316, 257170, 365065, 456688, 605532, 850096, 1071831 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 4*a(n-3) + a(n-5) - 3*a(n-6) - 3*a(n-8) - 4*a(n-9) + a(n-11) + 4*a(n-12) + 3*a(n-14) - 2*a(n-17) for n>19.
Empirical g.f.: x*(3 + 4*x + 5*x^2 - 2*x^3 - 3*x^4 - 9*x^5 - 5*x^6 - 13*x^7 - 6*x^8 - 12*x^9 + 7*x^10 + 12*x^11 + 26*x^12 + 8*x^13 - 8*x^14 - 17*x^15 - 5*x^16 + 5*x^17 + 2*x^18) / ((1 - x)*(1 + x)*(1 - x + x^2)*(1 + x + x^2)*(1 - x^2 - x^3)*(1 - 2*x^3)*(1 + x^2 - x^3 + x^4 - x^5)). - Colin Barker, Oct 29 2018
EXAMPLE
All solutions for n=4:
..3..3....3..3....3..3....3..3....3..2....3..2....3..3....3..2....3..3....3..3
..2..1....2..2....2..1....2..2....3..1....3..1....2..2....3..1....2..2....2..2
..3..3....3..1....3..3....3..1....2..2....2..1....3..3....2..2....3..1....3..1
..2..2....2..2....2..1....3..2....3..1....3..3....2..2....3..3....3..1....2..1
CROSSREFS
Column 2 of A240792.
Sequence in context: A260823 A359486 A135114 * A191647 A195131 A361666
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 12 2014
STATUS
approved

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Last modified August 22 23:56 EDT 2024. Contains 375369 sequences. (Running on oeis4.)