**Rohrbach's problem: a(n) is the largest integer such that there exists a set of n integers that is a basis of order 2 for (0, 1, ..., a(n)-1).**

*1, 3, 5, 9, 13, 17, 21, 27, 33, 41, 47, 5*

*2 seqfan posts*

Index of A-numbers in seqfan: by ascending order by month by frequency by keyword

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