A195002 Number of lower triangles of a 6 X 6 0..n array with each element differing from all of its horizontal and vertical neighbors by one.
2, 4608, 31042, 81014, 138956, 199988, 261324, 322806, 384292, 445780, 507268, 568756, 630244, 691732, 753220, 814708, 876196, 937684, 999172, 1060660, 1122148, 1183636, 1245124, 1306612, 1368100, 1429588, 1491076, 1552564, 1614052, 1675540
Offset: 1
Keywords
Examples
Some solutions for n=4: ..4............2............2............4............2............0 ..3.4..........3.2..........1.0..........3.4..........3.4..........1.2 ..2.3.2........4.3.2........0.1.0........2.3.4........4.3.2........2.3.4 ..1.2.3.2......3.2.3.4......1.2.1.2......3.4.3.4......3.4.3.2......1.2.3.2 ..0.1.2.3.2....2.3.4.3.2....0.1.0.1.2....2.3.2.3.2....2.3.2.1.2....2.1.2.1.2 ..1.2.1.2.1.0..3.4.3.4.3.2..1.2.1.2.1.2..3.2.3.2.3.2..3.2.3.2.1.0..3.2.3.2.1.2
Links
- R. H. Hardin, Table of n, a(n) for n = 1..200
Crossrefs
Cf. A194998.
Formula
Empirical: a(n) = 61488*n - 169100 for n>8.
Empirical g.f.: 2*x*(1 + 2302*x + 10914*x^2 + 11769*x^3 + 3985*x^4 + 1545*x^5 + 152*x^6 + 73*x^7 + 2*x^8 + x^9) / (1 - x)^2. - Colin Barker, May 06 2018
Comments