A224386 Number of nX3 0..3 arrays with diagonals and antidiagonals unimodal and rows nondecreasing.

20, 400, 6094, 86701, 1268572, 18794636, 279128617, 4142692993, 61481903024, 912523782542, 13544525098266, 201041292342421, 2984053971336637, 44292278131103241, 657430060365000621, 9758232360460992934

Offset: 1

Author

R. H. Hardin Apr 05 2013

Keywords

• nonn

Comments

Column 3 of A224391

Examples

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

Links

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

Formula

Empirical: a(n) = 20*a(n-1) -70*a(n-2) -211*a(n-3) +2453*a(n-4) -12192*a(n-5) +5907*a(n-6) +119292*a(n-7) -294992*a(n-8) +742820*a(n-9) +144828*a(n-10) -5072952*a(n-11) +6034728*a(n-12) -15994872*a(n-13) -858096*a(n-14) -10368*a(n-15)