Illustration of a(12) by Hugo Pfoertner, based on personal communication

from Peter Munn, 2017 Aug 23:

Peter wrote:
"I have an 860 area tiling with 12 equilateral triangles, 860 being A014529(12).
Whether there are other such 860 area tilings is a good question,
as I have found two 810 area tilings with 12 triangles.

This tiled 860 area has edges 13, 12, 12, 11, 14, 10 in order.
The 14 edge hosts two tiles of side 7, the other edges host a single tile.
A further tile of side 7 adjoins the other two.
A tile of side 4, two of side 3, and one of side 1 fill the centre."

  a(12) = 860



                              *---+---+---+---+---+---+---+---+---+---+---*
                             / \                                         / \
                            +   +                                       +   +
                           /     \                                     /     \
                          +       +                                   +       +
                         /         \                                 /         \
                        +           +                               +           +
                       /             \              11             /             \
                      +               +                           +               +
                     /                 \                         /                 \
                    +         7         +                       +                   +
                   /                     \                     /                     \
                  +                       +                   +                       +
                 /                         \                 /                         \
                *---+---+---+---+---+---+---*               +                           +
               / \                         / \             /                             \
              +   +                       +   +           +              12               +
             /     \                     /     \         /                                 \
            +       +         7         +       +       +                                   +
           /         \                 /    4    \     /                                     \
          +           +               +           +   +                                       +
         /             \             /             \ /                                         \
        +               +           *---+---+---*---*                                           +
       /                 \         / \         / \ /                                             \
      +         7         +       +   +   3   +   *---+---+---+---+---+---+---+---+---+---+---+---*
     /                     \     /     \     /     \                                             /
    +                       +   +   3   +   +       +                                           +
   /                         \ /         \ /         \                                         /
  *---+---+---+---+---+---+---*---+---+---*           +                                       +
   \                                     /             \                                     /
    +                                   +               +                                   +
     \                                 /                 \                                 /
      +                               +                   +                               +
       \                             /                     \             12              /
        +                           +                       +                           +
         \            10           /                         \                         /
          +                       +                           +                       +
           \                     /                             \                     /
            +                   +              13               +                   +
             \                 /                                 \                 /
              +               +                                   +               +
               \             /                                     \             /
                +           +                                       +           +
                 \         /                                         \         /
                  +       +                                           +       +
                   \     /                                             \     /
                    +   +                                               +   +
                     \ /                                                 \ /
                      *---+---+---+---+---+---+---+---+---+---+---+---+---*