login
A224129
Number of n X 4 0..1 arrays with rows nondecreasing and antidiagonals unimodal.
1
5, 25, 106, 419, 1635, 6392, 25047, 98221, 385194, 1510527, 5923295, 23227112, 91080915, 357157713, 1400531394, 5491938683, 21535675531, 84448377880, 331149514687, 1298544789829, 5092015833594, 19967447759719, 78298847269031
OFFSET
1,1
COMMENTS
Column 4 of A224133.
LINKS
FORMULA
Empirical: a(n) = 5*a(n-1) - 5*a(n-2) + 2*a(n-3) + 4*a(n-4).
Empirical g.f.: x*(5 + 6*x^2 + 4*x^3) / (1 - 5*x + 5*x^2 - 2*x^3 - 4*x^4). - Colin Barker, Aug 27 2018
EXAMPLE
Some solutions for n=3:
..0..0..1..1....0..0..0..1....1..1..1..1....1..1..1..1....0..1..1..1
..0..0..0..0....0..0..1..1....0..0..0..1....0..1..1..1....1..1..1..1
..0..0..0..0....1..1..1..1....0..0..0..1....0..0..1..1....0..0..0..0
CROSSREFS
Cf. A224133.
Sequence in context: A264018 A067971 A266424 * A111641 A074419 A247105
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 31 2013
STATUS
approved