Here is one example of pairing of players for the 19 weeks.
week no pair 1 pair 2 pair 3 pair 4 pair 5 pair 6 pair 7 pair 8
pair 9 pair 10
week 1: 1-20 2-19 3-18 4-17 5-16 6-15 7-14 8-13
9-12 10-11
week 2: 2-20 3-1 4-19 5-18 6-17 7-16 8-15 9-14
10-13 11-12
week 3: 3-20 4-2 5-1 6-19 7-18 8-17 9-16 10-15
11-14 12-13
week 4: 4-20 5-3 6-2 7-1 8-19 9-18 10-17 11-16
12-15 13-14
week 5: 5-20 6-4 7-3 8-2 9-1 10-19 11-18 12-17
13-16 14-15
week 6: 6-20 7-5 8-4 9-3 10-2 11-1 12-19 13-18
14-17 15-16
week 7: 7-20 8-6 9-5 10-4 11-3 12-2 13-1 14-19
15-18 16-17
week 8: 8-20 9-7 10-6 11-5 12-4 13-3 14-2 15-1
16-19 17-18
week 9: 9-20 10-8 11-7 12-6 13-5 14-4 15-3 16-2
17-1 18-19
week 10: 10-20 11-9 12-8 13-7 14-6 15-5 16-4
17-3 18-2 19-1
week 11: 11-20 12-10 13-9 14-8 15-7 16-6 17-5
18-4 19-3 1-2
week 12: 12-20 13-11 14-10 15-9 16-8 17-7 18-6
19-5 1-4 2-3
week 13: 13-20 14-12 15-11 16-10 17-9 18-8 19-7
1-6 2-5 3-4
week 14: 14-20 15-13 16-12 17-11 18-10 19-9 1-8
2-7 3-6 4-5
week 15: 15-20 16-14 17-13 18-12 19-11 1-10 2-9
3-8 4-7 5-6
week 16: 16-20 17-15 18-14 19-13 1-12 2-11 3-10
4-9 5-8 6-7
week 17: 17-20 18-16 19-15 1-14 2-13 3-12 4-11
5-10 6-9 7-8
week 18: 18-20 19-17 1-16 2-15 3-14 4-13 5-12
6-11 7-10 8-9
week 19: 19-20 1-18 2-17 3-16 4-15 5-14 6-13
7-12 8-11 9-10
Same thing in a more condensed format to (hopefully) avoid line length
problems
week 1: 1-20, 2-19, 3-18, 4-17, 5-16, 6-15, 7-14, 8-13, 9-12, 10-11
week 2: 2-20, 3-1, 4-19, 5-18, 6-17, 7-16, 8-15, 9-14, 10-13, 11-12
week 3: 3-20, 4-2, 5-1, 6-19, 7-18, 8-17, 9-16, 10-15, 11-14, 12-13
week 4: 4-20, 5-3, 6-2, 7-1, 8-19, 9-18, 10-17, 11-16, 12-15, 13-14
week 5: 5-20, 6-4, 7-3, 8-2, 9-1, 10-19, 11-18, 12-17, 13-16, 14-15
week 6: 6-20, 7-5, 8-4, 9-3, 10-2, 11-1, 12-19, 13-18, 14-17, 15-16
week 7: 7-20, 8-6, 9-5, 10-4, 11-3, 12-2, 13-1, 14-19, 15-18, 16-17
week 8: 8-20, 9-7, 10-6, 11-5, 12-4, 13-3, 14-2, 15-1, 16-19, 17-18
week 9: 9-20, 10-8, 11-7, 12-6, 13-5, 14-4, 15-3, 16-2, 17-1, 18-19
week 10: 10-20, 11-9, 12-8, 13-7, 14-6, 15-5, 16-4, 17-3, 18-2, 19-1
week 11: 11-20, 12-10, 13-9, 14-8, 15-7, 16-6, 17-5, 18-4, 19-3, 1-2
week 12: 12-20, 13-11, 14-10, 15-9, 16-8, 17-7, 18-6, 19-5, 1-4, 2-3
week 13: 13-20, 14-12, 15-11, 16-10, 17-9, 18-8, 19-7, 1-6, 2-5, 3-4
week 14: 14-20, 15-13, 16-12, 17-11, 18-10, 19-9, 1-8, 2-7, 3-6, 4-5
week 15: 15-20, 16-14, 17-13, 18-12, 19-11, 1-10, 2-9, 3-8, 4-7, 5-6
week 16: 16-20, 17-15, 18-14, 19-13, 1-12, 2-11, 3-10, 4-9, 5-8, 6-7
week 17: 17-20, 18-16, 19-15, 1-14, 2-13, 3-12, 4-11, 5-10, 6-9, 7-8
week 18: 18-20, 19-17, 1-16, 2-15, 3-14, 4-13, 5-12, 6-11, 7-10, 8-9
week 19: 19-20, 1-18, 2-17, 3-16, 4-15, 5-14, 6-13, 7-12, 8-11, 9-10
This is an example of a Round robin algorithm, see
http://www.devenezia.com/downloads/round-robin/index.html
The formula in cell B2 is this:
=1+MOD(ROW()+COLUMN()-4,19)&"-"&IF(COLUMN()=2,20,1+MOD(ROW()-COLUMN(),19))
Copy to the right until cell K2 and then down to row 20
Hope this helps / Lars-Åke