A223866 Number of 3Xn 0..3 arrays with rows and antidiagonals unimodal and columns nondecreasing.
20, 400, 4884, 41682, 273959, 1477240, 6818350, 27746619, 101698292, 341120712, 1060013078, 3081189588, 8443340635, 21952389700, 54443494785, 129382581759, 295772387822, 652604111790, 1393875593290, 2889329636208, 5825806879833
Offset: 1
Keywords
Examples
Some solutions for n=3 ..0..1..2....0..1..0....3..2..0....0..0..0....0..0..0....0..2..0....0..0..0 ..2..2..2....0..3..0....3..2..0....1..3..1....3..1..0....0..2..0....1..1..0 ..2..3..3....1..3..2....3..3..0....3..3..2....3..3..1....1..3..1....3..3..1
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = (1/3629463552000)*n^18 + (7/403273728000)*n^17 + (667/951035904000)*n^16 + (3281/174356582400)*n^15 + (148069/402361344000)*n^14 + (1366301/249080832000)*n^13 + (3748907/57480192000)*n^12 + (1190879/1916006400)*n^11 + (344761547/73156608000)*n^10 + (684241027/24385536000)*n^9 + (104051693257/804722688000)*n^8 + (54794329/119750400)*n^7 + (786440609/628992000)*n^6 + (81330893999/31135104000)*n^5 + (895703793151/217945728000)*n^4 + (8582457311/1816214400)*n^3 + (317136049/79168320)*n^2 + (10267897/6126120)*n + 1
Comments