N-let symmetries

Let us define a symmetrical configuration of N numbers (0,1,...,N-1) which satisfy the symmetry defined by N-lets such as the pairs (bi-lets) in the previous section. The required conditions for N-lets are itemized as follows.

• N-lets contains the lines of N-affine plain (for affine plains, refer Zwillinger(1996) [1],) thus and . These patterns are called primary N-lets in the text.
• N-lets are invariant to its rotation or transposition except primary N-lets. We call such N-lets as symmetrical N-lets.

These sections are showing N-lets and 2D digit-tilings satisfying N-let symmetry for N=3, 4, and 5.

 
• Triplets (3-lets)
• Tetralets (4-lets)
• Pentalets (5-lets)