login
A269285
Number of n X 4 0..3 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling three no more than once.
1
216, 19188, 1363572, 87559668, 5306911092, 309846524148, 17623065834612, 983118947312628, 54032675767734132, 2934733632740325108, 157871441490222209652, 8425105813832255961588, 446611038737537558861172
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 98*a(n-1) - 2401*a(n-2) for n>3.
Conjectures from Colin Barker, Jan 21 2019: (Start)
G.f.: 36*x*(1 - x)*(6 - 49*x) / (1 - 49*x)^2.
a(n) = 36 * (49^(n-2) * (240*n+53)) for n>1.
(End)
EXAMPLE
Some solutions for n=2:
..3..0..2..0. .3..1..1..3. .1..3..3..2. .3..2..0..2. .0..0..2..3
..2..0..2..3. .1..3..2..1. .3..3..3..0. .3..0..2..2. .2..2..2..0
CROSSREFS
Column 4 of A269289.
Sequence in context: A223359 A046234 A229408 * A133052 A365629 A078204
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 21 2016
STATUS
approved