login
A263366
Number of (n+1) X (1+1) 0..2 arrays with each row and column divisible by 7, read as a base-3 number with top and left being the most significant digits.
2
1, 1, 2, 5, 10, 19, 37, 73, 146, 293, 586, 1171, 2341, 4681, 9362, 18725, 37450, 74899, 149797, 299593, 599186, 1198373, 2396746, 4793491, 9586981, 19173961, 38347922, 76695845, 153391690, 306783379, 613566757, 1227133513, 2454267026, 4908534053
OFFSET
1,3
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) - 3*a(n-2) + 3*a(n-3) - 3*a(n-4) + 3*a(n-5) - 2*a(n-6).
Empirical g.f.: x*(1 - 2*x + 2*x^2 - x^3 + x^4 - 2*x^5) / ((1 - x)*(1 - 2*x)*(1 - x + x^2)*(1 + x + x^2)). - Colin Barker, Jan 01 2019
EXAMPLE
All solutions for n=4:
..2..1....0..0....2..1....0..0....2..1
..0..0....2..1....0..0....0..0....2..1
..2..1....0..0....0..0....0..0....0..0
..0..0....0..0....2..1....0..0....2..1
..2..1....2..1....0..0....0..0....2..1
CROSSREFS
Column 1 of A263373.
Sequence in context: A061705 A052944 A132736 * A068035 A304973 A016029
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 16 2015
STATUS
approved