A239406 Number of 2 X n 0..3 arrays with no element equal to one plus the sum of elements to its left or two plus the sum of the elements above it, modulo 4.

5, 23, 105, 478, 2165, 9811, 44399, 201006, 909679, 4117547, 18635613, 84347726, 381758761, 1727876419, 7820451787, 35395951502, 160204196803, 725095175067, 3281826924665, 14853766696750, 67229111585533, 304283379907315

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) + 12*a(n-2) - 18*a(n-3) - 29*a(n-4) + 19*a(n-5) + 38*a(n-6) + 8*a(n-7).

Empirical g.f.: x*(5 + 8*x - 24*x^2 - 23*x^3 + 30*x^4 + 42*x^5 + 8*x^6) / (1 - 3*x - 12*x^2 + 18*x^3 + 29*x^4 - 19*x^5 - 38*x^6 - 8*x^7). - Colin Barker, Oct 26 2018

Example

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

Crossrefs

Row 2 of A239405.

Sequence in context: A026760 A064914 A243873 * A107839 A270530 A128732

Adjacent sequences: A239403 A239404 A239405 * A239407 A239408 A239409

Keyword

nonn

Author

R. H. Hardin, Mar 17 2014

Status

approved