Problem Statement

The nth Motzkin number (denoted by M[n]) is the number of different ways of drawing non-intersecting chords between n points on a circle (not necessarily touching every point by a chord). By convention M[0] = 1.

Compute and show on this page the first 42 Motzkin numbers or, if your language does not support 64 bit integers, as many such numbers as you can. Indicate which of these numbers are prime.

Let's start with the solution:

motzkin[0]:1$
motzkin[1]:1$
motzkin[n]:=((2*n+1)*motzkin[n-1]+(3*n-3)*motzkin[n-2])/(n+2)$

/* Test cases */
makelist(motzkin[i],i,0,41);

sublist(%,primep);