A123931 a(n) = H(n)*n!/(floor(n/2))! (mod (n+1)), where H(n) = sum{k=1 to n} 1/k, the n-th harmonic number.

0, 1, 0, 3, 0, 5, 0, 2, 3, 4, 0, 0, 0, 6, 9, 0, 0, 0, 0, 0, 18, 10, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 30, 16, 0, 0, 0, 18, 24, 0, 0, 0, 0, 0, 0, 22, 0, 0, 0, 0, 12, 0, 0, 0, 0, 0, 54, 28, 0, 0, 0, 30, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 36, 0, 0, 0, 0, 0, 0, 0, 40, 0, 0, 0, 42, 51, 0, 0, 0, 0, 0, 3, 46, 0, 0, 0