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

1,1

Comments

Column 3 of A224391

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)

Example

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

Crossrefs

Sequence in context: A019319 A083276 A057745 * A189198 A224019 A171294

Adjacent sequences: A224383 A224384 A224385 * A224387 A224388 A224389

Keyword

nonn

Author

R. H. Hardin Apr 05 2013

Status

approved