Given a ring $R$ (with 1 and not necessarily commutative) when is the polynomial ring $R[x]$ semisimple?
For example if R is a Noetherian integral domain then R[x] is not semisimple. Indeed, $R[x]$ is Noetherian but then if we assume that $R[x]$ is semisimple this would imply that $R[x]$ is Artinian which is not.
Question: is there a ring $R$ (with $1$ and not necessarily commmutative) such that $R[x]$ is semisimple? or is $R[x]$ never semisimple for any ring $R$?