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A181948
Triangle read by rows: T(n,k) (2 <= k <= n) = dimension of partially ordered set of all 1-element and (k-1)-element subsets of an n-set.
0
2, 2, 3, 2, 3, 4, 2, 4, 4, 5, 2, 4, 5, 5, 6, 2, 4, 6, 6, 6, 7, 2, 4, 6, 7, 7, 7, 8, 2, 4, 6, 8, 8, 8, 8, 9, 2, 4, 6, 8, 9, 9, 9, 9, 10, 2, 4, 7, 9, 10, 10, 10, 10, 10, 11, 2, 4, 7, 9, 10, 11, 11, 11, 11, 11, 12, 2, 5, 7, 9, 11, 12, 12, 12, 12, 12, 12, 13, 2, 5, 7, 9, 12, 12, 13, 13, 13, 13, 13, 13, 14
OFFSET
2,1
REFERENCES
Trotter, William T., Jr. Some combinatorial problems for permutations. Proceedings of the Eighth Southeastern Conference on Combinatorics, Graph Theory and Computing (Louisiana State Univ., Baton Rouge, La., 1977), pp. 619--632. Congressus Numerantium, No. XIX, Utilitas Math., Winnipeg, Man., 1977. MR0480110 (58 #309).
EXAMPLE
Triangle begins:
2
2 3
2 3 4
2 4 4 5
2 4 5 5 6
2 4 6 6 6 7
2 4 6 7 7 7 8
2 4 6 8 8 8 8 9
2 4 6 8 9 9 9 9 10
2 4 7 9 10 10 10 10 10 11
2 4 7 9 10 11 11 11 11 11 12
2 5 7 9 11 12 12 12 12 12 12 13
2 5 7 9 12 12 13 13 13 13 13 13 14...
CROSSREFS
Sequence in context: A221999 A222334 A340716 * A238943 A070081 A366686
KEYWORD
nonn,tabl
AUTHOR
N. J. A. Sloane, Apr 03 2012
STATUS
approved