| Let Y_n be the set of trees of degree n. A nonempty subset of Y_n is called a
grove. The set of all groves of degree n is denoted by Y_n.
a(n) for n<= 7 given by right-most column of Table 1,
p. 3, of Bruno and Yasaki: The arithmetic of the natural numbers N can be extended
to arithmetic operations on planar binary trees. This gives rise to a
non-commutative arithmetic theory. In this exposition, we describe this
arithmetree, first defined by Loday and investigate prime trees.
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