On the number of lattice animals embeddable in the square lattice
Anthony John Guttmann · Journal of Physics A Mathematical and General · 1982
Enumeration of lattice animals embeddable in a square lattice has been extended to 24 cell animals by Redelmeier (1981). It is shown that the number of animals per site a n approximately 0.317(4.0626) n n -1 exp(-0.465 n -0.87 ) to a high degree of accuracy.