A214386 Number of 4X4X4 triangular 0..n arrays with no element lying outside the (possibly reversed) range delimited by its sw and se neighbors, and no element equal to its horizontal neighbors.
16, 890, 11048, 74260, 350232, 1305392, 4107248, 11363940, 28412824, 65439858, 140806952, 286079040, 553378176, 1025850192, 1832212128, 3166557496, 5314833216, 8689668506, 13875533864, 21686539292, 33239546824, 50045674976
Offset: 1
Keywords
Examples
Some solutions for n=3 .....3........2........2........2........2........3........2........2 ....3.2......1.2......3.0......2.3......2.1......2.3......0.2......1.2 ...1.3.0....0.1.2....3.2.0....0.3.2....2.1.2....1.3.0....0.1.2....0.3.2 ..0.1.3.0..1.0.3.2..3.0.3.0..0.1.3.1..2.0.1.3..0.3.0.2..0.2.1.2..0.2.3.0
Links
- R. H. Hardin, Table of n, a(n) for n = 1..163
Formula
Empirical: a(n) = (109/226800)*n^10 + (1531/90720)*n^9 + (6911/30240)*n^8 + (4553/3024)*n^7 + (27071/5400)*n^6 + (34159/4320)*n^5 + (409217/90720)*n^4 - (4937/4536)*n^3 - (22087/12600)*n^2 - (43/126)*n
Comments