A224059 Number of nX3 0..3 arrays with rows, columns and antidiagonals unimodal and diagonals nondecreasing.
50, 984, 8854, 58814, 324702, 1557606, 6643979, 25596389, 90177585, 293585050, 891208427, 2542007013, 6857916671, 17598839738, 43168340844, 101638636169, 230538577645, 505352928460, 1073534755140, 2215475595868, 4451276849868
Offset: 1
Keywords
Examples
Some solutions for n=3 ..3..0..0....0..0..0....0..0..2....2..2..1....1..1..0....1..1..1....2..0..0 ..3..3..1....1..1..0....1..1..2....1..2..3....1..1..1....0..1..3....1..3..2 ..0..3..3....1..2..3....1..1..3....0..2..3....0..1..2....0..1..3....1..1..3
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = (1/3629463552000)*n^18 + (1/80654745600)*n^17 + (673/1307674368000)*n^16 + (3163/237758976000)*n^15 + (208801/747242496000)*n^14 + (625841/149448499200)*n^13 + (1696897/28740096000)*n^12 + (14064731/28740096000)*n^11 + (339240647/73156608000)*n^10 + (339530671/14631321600)*n^9 + (4767368563/28740096000)*n^8 + (637757023/1026432000)*n^7 + (26329719541/10378368000)*n^6 + (2426824577/339655680)*n^5 + (343572662101/18162144000)*n^4 - (189957341011/9081072000)*n^3 + (1627071089/5834400)*n^2 - (2276993179/3063060)*n + 701 for n>3
Comments