A252516 Number of (n+2) X (1+2) 0..3 arrays with every 3 X 3 subblock row and column sum not equal to 0 2 4 6 or 7 and every 3 X 3 diagonal and antidiagonal sum equal to 0 2 4 6 or 7.

806, 791, 475, 660, 1093, 1471, 2176, 3809, 6101, 9098, 16197, 27215, 40668, 72707, 123525, 184674, 330481, 562847, 841564, 1506331, 2566837, 3838002, 6870033, 11708143, 17506412, 31336843, 53406693, 79855586, 142943489, 243616831

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-3) - 7*a(n-6) + 2*a(n-9) for n>14.

Empirical g.f.: x*(806 + 791*x + 475*x^2 - 4176*x^3 - 3653*x^4 - 1379*x^5 + 3858*x^6 + 2788*x^7 + 600*x^8 - 950*x^9 - 588*x^10 - 44*x^11 - 8*x^12 + 2*x^13) / ((1 - x)*(1 + x + x^2)*(1 - 5*x^3 + 2*x^6)). - Colin Barker, Dec 03 2018

Example

Some solutions for n=4:
..2..1..2....1..1..1....0..2..3....3..2..0....0..3..2....0..0..3....1..1..1
..3..2..0....2..1..0....2..1..2....0..2..3....3..3..2....1..2..2....0..1..2
..3..2..3....2..1..2....3..2..3....2..1..2....2..2..1....2..3..0....2..1..2
..2..1..2....1..3..1....3..2..3....3..2..3....3..3..2....2..3..3....1..3..1
..0..2..3....2..1..2....2..1..2....3..2..0....0..3..2....1..2..2....2..1..2
..3..2..3....2..1..2....0..0..3....2..1..2....2..2..1....2..0..3....2..1..0

Crossrefs

Column 1 of A252523.

Sequence in context: A267979 A249877 A252515 * A252523 A243858 A252682

Adjacent sequences: A252513 A252514 A252515 * A252517 A252518 A252519

Keyword

nonn

Author

R. H. Hardin, Dec 18 2014

Status

approved