A225342 Number of nX6 -1,1 arrays such that the sum over i=1..n,j=1..6 of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute 6-across galley oarsmen left-right at n fore-aft positions so that there are no turning moments on the ship).
1, 1, 3, 17, 81, 397, 2073, 11291, 63121, 360909, 2102597, 12439855, 74561687, 451920441, 2765717847, 17069622035, 106139191511, 664358517275, 4183117802521, 26479526009223, 168426949915891, 1076002461947039
Offset: 1
Keywords
Examples
Some solutions for n=4 .-1.-1.-1..1..1..1...-1.-1.-1..1..1..1...-1.-1.-1.-1..1..1...-1.-1.-1.-1.-1..1 .-1.-1.-1.-1..1..1...-1.-1..1..1..1..1...-1..1..1..1..1..1...-1..1..1..1..1..1 .-1..1..1..1..1..1...-1.-1.-1.-1.-1..1...-1.-1.-1.-1..1..1...-1..1..1..1..1..1 .-1.-1.-1.-1..1..1...-1.-1..1..1..1..1...-1.-1.-1..1..1..1...-1.-1.-1.-1.-1..1
Links
- R. H. Hardin, Table of n, a(n) for n = 1..112
Comments