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A054255 Triangle T(n,k) (n >= 1, 0<=k<=n) giving number of preferential arrangements of n things beginning with k (transposed, then read by rows). 1
1, 1, 2, 2, 5, 6, 6, 18, 25, 26, 24, 84, 134, 149, 150, 120, 480, 870, 1050, 1081, 1082, 720, 3240, 6600, 8700, 9302, 9365, 9366, 5040, 25200, 57120, 82320, 92526, 94458, 94585, 94586, 40320, 221760, 554400, 871920, 1038744, 1085364, 1091414 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Can be generated from Stirling_2 triangle A008277 (cf. A028246, which is intermediate between the two arrays).

LINKS

Table of n, a(n) for n=1..43.

N. J. A. Sloane and Thomas Wieder, The Number of Hierarchical Orderings, Order 21 (2004), 83-89.

EXAMPLE

1;

1,  2;

2,  5,  6;

6, 18, 25, 26; ...

CROSSREFS

Row sums give A000670. First 3 rows are A000629, A002050 = A000629 - 1, 2*A002051 = (A000629 - 2^m) (m >= 0)

Sequence in context: A209744 A209465 A209527 * A063177 A249521 A034803

Adjacent sequences:  A054252 A054253 A054254 * A054256 A054257 A054258

KEYWORD

nonn,tabl

AUTHOR

Eugene McDonnell (Eemcd(AT)aol.com), May 05 2000

EXTENSIONS

More terms from James A. Sellers, May 05 2000

STATUS

approved

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Last modified January 20 17:05 EST 2019. Contains 319335 sequences. (Running on oeis4.)