\begin{definition}[Definition:Biquadrate]
A '''biquadrate number''' (or just '''biquadrate''') is a number which can be expressed as the fourth power of an integer.
The sequence of positive '''biquadrates''' begins:
:$1, 16, 81, 256, 625, 1297, 2401, 4096, 6561, 10000, \ldots$
{{OEIS|A000583}}
\end{definition}