Indecomposable doubling for representations of the type I Lie superalgebras sl(m/n) and osp(2/2n)

We establish that for the type I Lie superalgebras $sl(m/n)$ and $osp(2/2n)$, each Kac module admits a 1 parameter family of indecomposable double extensions. The result follows from explicit evaluation $H^1$ superalgebra cohomology valued in tensor product its dual.