A215866 Number of permutations of 0..floor((n*6-2)/2) on odd squares of an n X 6 array such that each row, column, diagonal and (downwards) antidiagonal of odd squares is increasing.
1, 5, 12, 78, 189, 1233, 2988, 19494, 47241, 308205, 746892, 4872798, 11808549, 77040153, 186696108, 1218024054, 2951712081, 19257264405, 46667304972, 304462158318, 737821743309, 4813622739873, 11665145978028, 76104577363014
Offset: 1
Keywords
Examples
Some solutions for n=4: ..x..0..x..1..x..4....x..0..x..2..x..3....x..0..x..2..x..3....x..0..x..2..x..3 ..2..x..3..x..5..x....1..x..4..x..6..x....1..x..4..x..7..x....1..x..4..x..6..x ..x..6..x..8..x.10....x..5..x..8..x..9....x..5..x..8..x..9....x..5..x..7..x..8 ..7..x..9..x.11..x....7..x.10..x.11..x....6..x.10..x.11..x....9..x.10..x.11..x
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = 16*a(n-2) -3*a(n-4).
Empirical: g.f.: -x*(x-1)*(2*x^2+6*x+1) / ( 1-16*x^2+3*x^4 ). - R. J. Mathar, Nov 27 2015
Comments