If I have two spin-halves, then \begin{align} \frac{1}{2} \otimes \frac{1}{2} = 0 \oplus 1. \end{align} If I have three spin-halves, then \begin{align} \frac{1}{2} \otimes \frac{1}{2} \otimes \frac{1}{2} = \frac{1}{2} \oplus \frac{1}{2} \oplus \frac{3}{2}, \end{align} and for four \begin{align} \frac{1}{2} \otimes\frac{1}{2} \otimes \frac{1}{2} \otimes \frac{1}{2} = 0 \oplus 0 \oplus 1 \oplus 1 \oplus 1 \oplus 2. \end{align}
What's the decomposition into irreducible representations for $N$ (say even) spin-1/2s? That is, how many spin-$0$s do I get, how many spin-$1$s, how many spin-$2$s etc... There will be only one spin-$N/2$.
Of course one can solve this by induction, but on the off-chance that someone knows what it is by heart?
