A223956 Number of nX3 0..3 arrays with antidiagonals unimodal and rows and diagonals nondecreasing

20, 295, 3471, 41006, 485714, 5777663, 68892600, 822141033, 9813968785, 117159879996, 1398692077165, 16698106010927, 199348287106117, 2379894628461976, 28412070357384947, 339193873130519142

Offset

1,1

Comments

Column 3 of A223961

Links

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

Formula

Empirical: a(n) = 20*a(n-1) -105*a(n-2) +51*a(n-3) +589*a(n-4) +1340*a(n-5) -8833*a(n-6) -2855*a(n-7) +30423*a(n-8) +57774*a(n-9) -140760*a(n-10) -176184*a(n-11) +106272*a(n-12) +544320*a(n-13)

Example

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

Crossrefs

Sequence in context: A016259 A271029 A047795 * A132168 A069326 A001708

Adjacent sequences: A223953 A223954 A223955 * A223957 A223958 A223959

Keyword

nonn

Author

R. H. Hardin Mar 29 2013

Status

approved