|
|
A238039
|
|
Number of (n+1) X (1+1) 0..2 arrays with the upper median minus the lower median of every 2 X 2 subblock differing from its horizontal and vertical neighbors by exactly one.
|
|
1
|
|
|
81, 340, 1440, 6064, 25948, 109200, 466296, 1962720, 8385248, 35292928, 150759392, 634547840, 2710688576, 11409244416, 48737830912, 205137173504, 876305679104, 3688361604096, 15755932345856, 66316572940288, 283291082594304
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
FORMULA
|
Empirical: a(n) = 8*a(n-2) + 152*a(n-4) + 472*a(n-6) + 384*a(n-8).
Empirical g.f.: x*(81 + 340*x + 792*x^2 + 3344*x^3 + 2116*x^4 + 9008*x^5 + 1600*x^6 + 6912*x^7) / ((1 + 6*x^2)*(1 - 14*x^2 - 68*x^4 - 64*x^6)). - Colin Barker, Oct 24 2018
|
|
EXAMPLE
|
Some solutions for n=5:
..2..1....2..1....1..0....1..1....2..2....2..1....0..2....0..2....1..1....2..2
..2..2....0..0....1..0....2..0....2..2....0..0....2..2....2..0....0..2....2..0
..1..0....2..0....2..1....1..0....1..1....0..0....1..1....1..2....0..1....1..0
..1..1....1..0....0..2....1..2....0..2....1..2....1..0....1..0....2..1....0..0
..2..2....1..2....0..2....0..2....1..2....0..1....2..0....2..2....2..1....2..1
..2..1....2..1....1..2....2..0....1..1....0..1....2..2....2..0....1..1....2..2
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|