A238991 Number of n X 2 0..3 arrays with no element equal to two plus the sum of elements to its left or two plus the sum of the sum of elements above it, modulo 4.

7, 41, 203, 955, 4393, 20015, 90841, 411621, 1863915, 8437893, 38193735, 172873711, 782450381, 3541446587, 16028869589, 72547812889, 328356354383, 1486162751697, 6726470705667, 30444448197731, 137793568150513, 623662712572871

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) + a(n-2) - 48*a(n-3) + 49*a(n-4) + 70*a(n-5) - 77*a(n-6) - 68*a(n-7) + 52*a(n-8) + 16*a(n-9).

Empirical g.f.: x*(7 - x - 50*x^2 + 32*x^3 + 85*x^4 - 53*x^5 - 80*x^6 + 52*x^7 + 16*x^8) / ((1 - x)*(1 - 2*x)*(1 - 3*x - 12*x^2 + 18*x^3 + 29*x^4 - 19*x^5 - 38*x^6 - 8*x^7)). - Colin Barker, Oct 24 2018

Example

Some solutions for n=5:
..0..3....0..1....3..0....3..0....0..3....0..1....3..0....0..3....0..1....3..0
..3..2....3..0....0..0....3..0....3..3....0..0....0..0....0..3....0..0....0..3
..3..0....3..0....0..0....3..3....0..1....0..1....0..3....1..2....3..0....3..0
..1..2....1..0....0..0....1..2....3..2....0..1....3..3....1..1....3..0....1..0
..3..0....3..0....0..1....1..0....3..2....1..0....3..3....1..1....1..1....0..3

Crossrefs

Column 2 of A238997.

Sequence in context: A237854 A219862 A366996 * A084779 A266887 A237664

Adjacent sequences: A238988 A238989 A238990 * A238992 A238993 A238994

Keyword

nonn

Author

R. H. Hardin, Mar 08 2014

Status

approved