Bessel Polynomials

n Polynomial
1 (s+1)
2 (s2+3s+3)
3 (s+2.322)(s2+3.678s+6.460)
4 (s2+5.792s+9.140)(s2+4.208s+11.488)
5 (s+3.647)(s2+6.704s+14.273)(s2+4.649s+18.156)
6 (s2+8.497s+18.801)(s2+7.471s+20.853)(s2+5.032s+26.514)