References to A156989

Largest size of a subset of {1,2,3}^n that does not contain any combinatorial lines (i.e. strings formed by 1, 2, 3, and at least one instance of a wildcard x, with x then substituted for 1, 2, or 3, e.g. 12x3x gives the combinatorial line 12131, 12232, 12333.)
1, 2, 6, 18, 52, 150, 45

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