  The pairing interaction among identical nucleons in a single-particle level
is treated in the hamiltonian formalism using even Grassmann variables. A
minimal (irreducible) basis having a remarkable symmetry property is set up
using composite, commuting variables with a finite index of nilpotency.
Eigenvalues and eigenfunctions of given energy, seniority and zero third
component of the angular momentum of the pairing hamiltonian are then found.
The eigenvectors, which cannot be cast solely in terms of composite bosons with
angular momentum zero and two, are expanded in the minimal basis with
coefficients analytically expressed in terms of a generalized hypergeometric
function.
