Direct product of Z16 and Z4

Definition
This group can be defined as the uses as intermediate construct::external direct product of the cyclic group of order sixteen and the cyclic group of order four. Alternatively, it has the presentation:

$$G := \langle a,b \mid a^{16} = b^4 = e, ab = ba \rangle$$.

As an abelian group of prime power order
This group is the abelian group of prime power order corresponding to the partition:

$$\! 6 = 4 + 2$$

In other words, it is the group $$\mathbb{Z}_{p^4} \times \mathbb{Z}_{p^2}$$.

Other descriptions
The group can be defined using GAP's CyclicGroup and DirectProduct functions as:

DirectProduct(CyclicGroup(16),CyclicGroup(4))