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A241307
Number of 2Xn 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 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
5, 6, 15, 25, 40, 89, 121, 237, 390, 682, 1250, 2069, 3698, 6352, 11013, 19408, 33478, 58524, 101542, 176797, 307761, 535313, 932344, 1620570, 2821554, 4908976, 8540842, 14866293, 25861744, 45006289, 78311151, 136266311, 237120535
OFFSET
1,1
COMMENTS
Row 2 of A241306
LINKS
FORMULA
Empirical: a(n) = 2*a(n-2) +3*a(n-3) -a(n-4) -a(n-5) +2*a(n-6) -10*a(n-8) -7*a(n-9) +8*a(n-10) +5*a(n-11) -3*a(n-12) -7*a(n-13) +7*a(n-14) for n>20
EXAMPLE
Some solutions for n=4
..3..2..3..2....3..2..3..3....3..2..3..3....2..3..3..2....3..2..2..2
..3..1..1..2....3..0..1..2....3..1..1..2....2..1..1..2....3..0..0..1
CROSSREFS
Sequence in context: A227066 A115908 A247962 * A185876 A356496 A091020
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 18 2014
STATUS
approved