A205660 - OEIS

A205660

Number of 3X(n+1) 0..3 arrays with every 2 X 2 subblock having the same number of clockwise edge increases as its horizontal neighbors and no 2 X 2 subblock having the same number of counterclockwise edge increases as its vertical neighbors.

2120, 12296, 95008, 839872, 7919128, 76028256, 732727336, 7068433736, 68201154272, 658081945168, 6349980210408, 61272516345744, 591233822472776, 5704963557044152, 55048626862970856, 531178036521593464

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OFFSET

1,1

COMMENTS

Row 2 of A205659.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 12*a(n-1) -7*a(n-2) -173*a(n-3) +94*a(n-4) +1137*a(n-5) +190*a(n-6) -3906*a(n-7) -4350*a(n-8) +5407*a(n-9) +16999*a(n-10) +5544*a(n-11) -28150*a(n-12) -28396*a(n-13) +18360*a(n-14) +34596*a(n-15) -399*a(n-16) -17679*a(n-17) -2832*a(n-18) +5324*a(n-19) +1556*a(n-20) -636*a(n-21) -240*a(n-22) for n>26.

EXAMPLE

Some solutions for n=4:

..2..0..0..1..0....1..3..0..1..1....1..2..0..1..3....3..1..3..3..3

..3..2..1..3..1....0..1..2..0..2....1..3..2..0..2....1..1..1..1..1

..2..2..3..3..1....3..3..2..1..3....2..2..2..2..2....1..1..1..1..1

CROSSREFS

Sequence in context: A031770 A031680 A031544 * A205949 A205460 A263510

Adjacent sequences: A205657 A205658 A205659 * A205661 A205662 A205663

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 30 2012

STATUS

approved