84021990

Appears in sequences

• Number of symmetric non-crossing connected graphs on n equidistant nodes on a circle.at n=19A089073
• a(n) = binomial(6*n, 3*n)*binomial(3*n, n)/(2*(2*n+1)*binomial(2*n, n)).at n=4A176898
• a(n) = (30*n)!*(5*n)!*(3*n)!/((15*n)!*(12*n)!*(10*n)!*n!).at n=1A295465