It is shown that there exists a resolvable
n
2 by 4 orthogonal array which is invariant under the Klein 4-group
K
4 for all positive integers
n congruent to 0 modulo 4 except possibly for
n 
{12, 24, 156, 348}.
AMS (1980) subject classification Primary 05B05 - Secondary 51E05, 62K10