Mixed orthogonal arrays of strength two and size s are constructed by grouping points in the finite projective geometry . can be partitioned into   1, PG mn s   1, PG mn s       1 1 mn n s s         –1 n -flats such that each   –1 n flat is associated with a point in . An orthogonal array  1, n PG m s        1 1 mn n mn s s n s L s         can be constructed ...

We study integer sequences and transforms that operate on them. Many of these transforms are defined by triangular arrays of integers, with a particular focus on Riordan arrays and Pascal-like arrays. In order to explore the structure of these transforms, use is made of methods coming from the theory of continued fractions, hypergeometric functions, orthogonal polynomials and most importantly f...

Compound orthogonal arrays (COAs) and single arrays are alternatives to the inner–outer arrays advocated by Taguchi for robust parameter design experiments. A criterion based on the wordtype pattern and strength of COAs is proposed to select optimal COAs. Single arrays are classified into prodigal single arrays (PSAs) and economical single arrays (ESAs) according to their relative estimation ca...