(x + 1)!
gamma(2 + x)*polygamma(0, 2 + x)
/ 2 \ \polygamma (0, 2 + x) + polygamma(1, 2 + x)/*gamma(2 + x)
/ 3 \ \polygamma (0, 2 + x) + 3*polygamma(0, 2 + x)*polygamma(1, 2 + x) + polygamma(2, 2 + x)/*gamma(2 + x)