A198889 Square array in A071223 read by antidiagonals.
2, 2, 2, 2, 6, 2, 2, 12, 6, 2, 2, 20, 24, 6, 2, 2, 30, 72, 24, 6, 2, 2, 42, 172, 120, 24, 6, 2, 2, 56, 352, 480, 120, 24, 6, 2, 2, 72, 646, 1512, 720, 120, 24, 6, 2, 2, 90, 1094, 3976, 3600, 720, 120, 24, 6, 2, 2, 110, 1742, 9144, 14184, 5040, 720, 120, 24, 6, 2, 2, 132, 2642, 18990, 45992, 30240, 5040, 720, 120
Offset: 2
Examples
Array begins 2 2 2 2 2 ... 2 6 6 6 6 ... 2 12 24 24 24 ... 2 20 72 120 120 ... 2 30 172 480 720 ... ...
Links
- T. M. Cover, The number of linearly inducible orderings of points in d-space, SIAM J. Applied Math., 15 (1967), 434-439.
Crossrefs
Cf. A071223.
Programs
-
Maple
A071223 := proc(n,k) if k=1 and n>=2 then 2 elif n=2 and k>=1 then 2 elif k>=n-1 then n! else procname(n-1, k)+(n-1)*procname(n-1, k-1) fi ; end proc: for d from 3 to 16 do for k from 1 to d-2 do n := d-k ; printf("%d,",A071223(n,k)) ; end do: end do; # R. J. Mathar, Oct 31 2011
Formula
See A071223, which is the main entry for this array.