Using a newly suggested algorithm of Gozzi, Reuter and Thacker for cal
culating the excited states of one-dimensional systems, we determine a
pproximately the eigenvalues and eigenfunctions of the anharmonic osci
llator, described by the Hamiltonian H = 1/2p2+gx4. We use ground stat
e post-Gaussian trial wave functions of the form PSI(x) = N exp(-b\x\2
n), where n and b are continuous variational parameters. This algorith
m is based on the hierarchy of Hamiltonians related by supersymmetry (
SUSY) and the factorization method. We find that our two-parameter fam
ily of trial wave functions yields excellent energy eigenvalues and wa
ve functions for the first few levels of the anharmonic oscillator.