=
| 1 |
| (n+1)+1 |
| 1 |
| (n+1)+2 |
| 1 |
| (n+1)+3 |
| 1 |
| 3(n+1) |
| 1 |
| n+1 |
| 1 |
| n+2 |
| 1 |
| n+3 |
| 1 |
| 3n |
=
| 1 |
| 3n+1 |
| 1 |
| 3n+2 |
| 1 |
| 3n+3 |
| 1 |
| n+1 |
=
| 1 |
| 3n+1 |
| 1 |
| 3n+2 |
| 2 |
| 3n+3 |
故选C．
| 1 |
| n+1 |
| 1 |
| n+2 |
| 1 |
| n+3 |
| 1 |
| 3n |
| 1 |
| 3n+1 |
| 1 |
| 3n+2 |
| 1 |
| 3n+1 |
| 1 |
| 3n+2 |
| 2 |
| 3n+3 |
| 1 |
| 3n+1 |
| 1 |
| 3n+2 |
| 1 |
| (n+1)+1 |
| 1 |
| (n+1)+2 |
| 1 |
| (n+1)+3 |
| 1 |
| 3(n+1) |
| 1 |
| n+1 |
| 1 |
| n+2 |
| 1 |
| n+3 |
| 1 |
| 3n |
| 1 |
| 3n+1 |
| 1 |
| 3n+2 |
| 1 |
| 3n+3 |
| 1 |
| n+1 |
| 1 |
| 3n+1 |
| 1 |
| 3n+2 |
| 2 |
| 3n+3 |