Fig. 2: FREE LATTICE EXTENSION OF COMPLEMENTED DISTRIBUTIVE LATTICE ON 30
(PL p. 146, Lattice Theory, Garett Birkhoff, on "Free distributive lattice". To Birkhoff, a complemented distributive lattice (CDL) always has what is labeled (in this dictionary ) as a MAX and a MIN: elements not generated from "lattice atoms" (PL), rather assigned. So the number of elements in such a CDL -- or the free lattice drrived from it -- is always two more than our formulations. Thus, on this page, Birkhoff writes f(3) = 20 for the free CDL on 3 atoms. Then, ignoring the MAX, MIN, find 20 - 2 = 18, agreeing with what is found below.)
                                               30 (RANK 7)
                                               /\
                                              / |\
                                             /  | \
                                            /   |  \
                                           /    |   \
                                          /     |    \
                                         6     10     15 (RANK 6)
                                        /      /|\     \
                                       /      / | \     \
                                      /      /  |  \     \
                                      |     /   |   \     \
                                      |    /    |    \     \
                                      |   /     |     \    |
                                      |  /      |      \   |
                                      610     615     1015 (RANK 5)
                                     / \        |\        \  \__________
                                    /   \       | \________\_________  |
                                   /     \______|___________\_______ |  |
                                  /             |            \      \|  |
                                 2              3             5    61015 (RANK 4)
                                / \            /|\            /\
                               /   \          / | \          /  \
                              /     \        /  |  \        /    \
                             /       \      /   |   \      /      \
                            /         \    /    |    \    /        \
                           /           \  /     |     \  /          \
                          /             \/      |      \/            \
                     (23)(25)        (23)        (35)     (25)(35) (RANK 3)
                        | \   \        /        |        \        /   /   |
                        |  \   \      /         |         \      /   /    |
                        |   \   \    /          |          \    /   /     |
                        |    \   \  /           |           \  /   /      |
                        |     \   \/            |            \/   /       |
                        |      \  /\            |            /\  /        |
                        |       \/  \           |           /  \/         |
                        |       /\   \          |          /   /\         |
                        |      /  \   \         |         /   /  \        |
                        |     /    \   \        |        /   /    \       |
                        | ___/______\___\_______|_______/_ _/      \      |
                        ||  /        \   \      |      /            \     |
                        || /          \___\_____|_____/______________\__  |
                        ||/                \    |    /                \ | |                       
                      2  3                 2    5                  3  5 (RANK 2)
                        |                       |                         |
                        |                       |                         |
                        |                       |                         |                     
                        |                       |                         |    
                        |                       |                         |    
                        |                       |                         |  
                        -------------------2  3  5 (RANK 1)----------------------
                                                |
                                                |
                                                1 (RANK 0)

Please note the Rank-Ballot Distribution: 1, 3, 3, 4, 3, 3, 1 -- definitely not Binomial. (PL free database.)