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A081316
Lexicographically earliest sequence of positive integers such that n occurs a(n)-1 times, starting at n=1.
a(1)=2 because a(1)=1 would create a contradiction (1 would have appeared twice in the two sequences, not once). a(1)=2 implies that 1 appears once in this sequence; the first term that can equal 1 without creating a contradiction is a(4).
CROSSREFS
A081315 is the corresponding sequence for nonnegative integers, see also A001462.