A239040 Number of n X 1 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, modulo 4.

3, 7, 16, 38, 90, 212, 500, 1180, 2784, 6568, 15496, 36560, 86256, 203504, 480128, 1132768, 2672544, 6305344, 14876224, 35097536, 82805760, 195363968, 460923008, 1087457536, 2565643008, 6053132032, 14281179136, 33693644288, 79493552640

Offset

1,1

Comments

Column 1 of A239047.

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 2*a(n-3).

Empirical g.f.: x*(3 + x + 2*x^2) / (1 - 2*x - 2*x^3). - Colin Barker, Feb 24 2018

Example

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

Crossrefs

Cf. A239047.

Sequence in context: A192665 A052967 A297498 * A323225 A293065 A211278

Adjacent sequences: A239037 A239038 A239039 * A239041 A239042 A239043

Keyword

nonn

Author

R. H. Hardin, Mar 09 2014

Status

approved