Volume 9 (1998), pp. 245–259
The last sentence of §3.2 should read as follows:
For n=4, the splitting yields six such linear PDEs from the coefficients of the
terms involving Y(6), Y(4),
Y(5), Y(5), Y(4)3,
Y(4)2 and Y(4).
In the first paragraph of §6, the penultimate sentence should read as follows:
For an nth-order scalar ODE the determining equations are a linear system of PDEs
consisting of the adjoint of the determining equation for symmetries of the nth-order
ODE and additional equations when n[ges ]2.
We apologise for the errors in the above paper and hope that no inconvenience has been
caused to readers.