A224008 Number of n X 4 0..2 arrays with rows nondecreasing and antidiagonals unimodal.

15, 225, 2661, 28541, 297859, 3094127, 32148473, 334179881, 3474343713, 36122604265, 375565139165, 3904724751131, 40597113853797, 422084894246843, 4388382334042279, 45625654988950821, 474366234758987515

Offset

1,1

Comments

Column 4 of A224012.

Links

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

Formula

Empirical: a(n) = 15*a(n-1) - 58*a(n-2) + 105*a(n-3) + 20*a(n-4) - 183*a(n-5) + 220*a(n-6) + 240*a(n-7).

Empirical g.f.: x*(15 + 156*x^2 + 101*x^3 + 157*x^4 + 460*x^5 + 240*x^6) / (1 - 15*x + 58*x^2 - 105*x^3 - 20*x^4 + 183*x^5 - 220*x^6 - 240*x^7). - Colin Barker, Aug 26 2018

Example

Some solutions for n=3:
..0..0..2..2....0..1..1..2....1..1..1..2....1..2..2..2....0..0..0..1
..0..0..2..2....1..2..2..2....0..1..1..1....0..0..0..0....0..2..2..2
..0..0..0..2....2..2..2..2....0..1..2..2....0..0..1..1....0..1..1..1

Crossrefs

Cf. A224012.

Sequence in context: A223921 A224191 A224349 * A012852 A171289 A262336

Adjacent sequences: A224005 A224006 A224007 * A224009 A224010 A224011

Keyword

nonn

Author

R. H. Hardin, Mar 30 2013

Status

approved