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
KEYWORD
nonn,tabl
AUTHOR
N. J. A. Sloane, Apr 03 2012
STATUS
approved