A224129 Number of n X 4 0..1 arrays with rows nondecreasing and antidiagonals unimodal.

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

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

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

Adjacent sequences: A224126 A224127 A224128 * A224130 A224131 A224132

Keyword

nonn

Author

R. H. Hardin, Mar 31 2013

Status

approved