590413824

Appears in sequences

• Number of 2-enumeration of 4n X 4n quarter-turn symmetric alternating-sign matrices.at n=4A059487
• a(0) = 1, a(n) = harmonic_mean(a(n-1), n), where harmonic_mean(p, q) = 2/(1/p + 1/q); numerators.at n=16A353250