There are three types of research—

When N=9≡0(mod3),

When N= 10≡ 1 (mod3),

When N = 1 1≡2(mod3).

These three colors are: a, b and c.

For the arrangement and combination of dyeing methods when N=9≡0(mod3), as shown in the figure.

The dyeing method of (1) inner ring is ABC cycle, which is the starting point of other dyeing methods.

(2) There are two basic types of central dyeing method, which are located in the position of numerator and denominator respectively.

The staining method of (1) molecular position is 1 A followed by BC cycle;

(2) The staining method of molecular position is 1 A followed by BC cycle.

(3) According to the arrangement of four deformation dyeing methods of the outer ring, each section is divided into four zones in counterclockwise order, and each zone is arranged with one dyeing method.

The area (1) was replaced by 1 c in the BC cycle;

(2) the second area is replaced by a1thb in the CB cycle;

(3) the third zone in 3)BC cycle is replaced by a second c;

(4) the fourth region is replaced by the second b in the CB cycle with a;

There will be 3-6 c and b replaced by a,

So when n 9, there are n-3 = 9-3 = 6 C's, and 6 B's are replaced by A's respectively.

* * * There are (3- 1) (n-3) = 2 (n-3) = 2n-6 species.

(4) Not drawn,

1 and the third * * 2 c, 1 and the fifth * * 2 c in (1)BC cycle are 2×3=6 dyeing methods respectively.

(2) The 1 and the 3rd * * 2bs, the 1 and the 5th * * * 2bs, the 3rd and 5th * * * 2bs in the 2)CB cycle, totaling 2×3=6 dyeing methods, respectively.

The last two *** 12 staining methods,

What is provided above is the idea of permutation and combination of dyeing methods. When N= 10≡ 1(mod3)

And when N = 1 1≡2(mod3).

c？

B C？ b？ c？ b？ C

b？ b？ B

C C B B C C

B B

C B/CA？ c？ C/B？ C

c？ b？ b？ Answer?

b？ A

British Broadcasting Corporation

c？ Answer? c？ C

b？ b？ B

Answer? A/A？ C/B？ B

Answer? A B/C A？ C

? Answer? b？ barium

c？ C