Pell numbers

This is the sequence of Pell numbers made from Lego.

Again the colours repeat in regular patterns.

$P_2 | P_2, P_4, P_8, \ldots$

$P_3 | P_3, P_6, P_9, \ldots$

$P_4 | P_4, P_8, P_{12}, \ldots$

$P_5 | P_5, P_{10}, P_{15}, \ldots$

So this is almost exactly like the counting numbers. The 'P-primes' are P₂,P₃, P₅, P₇, ...