**a(n) = the sign of r(n), where r(n) is the integer in [ -2n,2n] which is congruent to (2n)! modulo 4n+1**

*0, 1, 1, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, *

*5 seqfan posts*

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

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