A087644 - OEIS

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A087644

Triangle T(n,k) (n >= 2, 1 <= k <= n) read by rows: (1/2) times number of linearly inducible orderings of n points in k-dimensional Euclidean space.

1, 1, 3, 1, 6, 12, 1, 10, 36, 60, 1, 15, 86, 240, 360, 1, 21, 176, 756, 1800, 2520, 1, 28, 323, 1988, 7092, 15120, 20160, 1, 36, 547, 4572, 22996, 71856, 141120, 181440, 1, 45, 871, 9495, 64144, 278820, 787824, 1451520, 1814400, 1, 55, 1321, 18205, 159094

(list; table; graph; refs; listen; history; text; internal format)

OFFSET

2,3

COMMENTS

Equals A071223/2. See that entry for further information.

LINKS

Table of n, a(n) for n=2..51.

T. M. Cover, The number of linearly inducible orderings of points in d-space, SIAM J. Applied Math., 15 (1967), 434-439.

MAPLE

T:=proc(n, k) if k>=n then 0 elif k=1 and n>=2 then 1 elif n=2 and k>=1 then 1 elif k=n-1 then n!/2 else T(n-1, k)+(n-1)*T(n-1, k-1) fi end:seq(seq(T(n, k), k=1..n-1), n=2..12);

CROSSREFS

Cf. A071223.

Sequence in context: A106855 A064282 A267849 * A049964 A143984 A051124

Adjacent sequences: A087641 A087642 A087643 * A087645 A087646 A087647

KEYWORD

nonn,tabl,easy

AUTHOR

N. J. A. Sloane, Oct 26 2003

EXTENSIONS

More terms from Emeric Deutsch, May 24 2004

STATUS

approved