**Triangular array, read by rows, where if n is odd the n-th row consists of n least unused non-primes, while if n is even the n-th row consists of the n least unused primes.**

*1, 2, 3, 4, 6, 8, 5, 7, 11, 13, 9, 10, 12, 14, 15, 17, 19, 23, 29, 31, 37, 16, 18, 20, 21, 22*

*1 seqfan posts*

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

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