  The log-periodic equation for the entropy $S = - (k/a) \sum_{i=1}^{N} p_{i}
\sin(a \ln p_{i})$, based on the forgotten Sharma-Taneja entropy measure, is
studied for the first time with $N$ the total number of system states and
$p_{i}$ the associated probabilities. It is argued that an oscillatory regime
for $S$ could in principle be understood in terms of a linear time-dependent
behavior for the associated probabilities in analogy with a spring system of
frequency $w$ gaining momentum from the surroundings. The physical meaning for
the production of entropy given by the parameter $a$ relates the angle $\omega
t$. We discuss its properties, and make a connection with the non-extensive
Tsallis, R\'{e}nyi, Boltzmann-Gibbs and Shannon entropies as special limiting
cases for systems with constant mass. Our non-trivial form of entropy displays
peculiar concavity and addition properties. Log-periodicity in $S$, concavity
lost, and non-additivity are manifested by increasing the value of the
coefficient $a$, which sets the variations with respect to the behavior of the
monotonic Gibbs entropy function. We have considered systems with linearly
increasing mass and have explained how "oscillating entropy" in such systems
may appear.
