Maximum number of intercalates in an rotated semicyclic diagonal Latin squares of order n, https://oeis.org/Axxxxxx

n=1, a(1)=0
Announcement: https://vk.com/wall162891802_2443, Eduard I. Vatutin, Jul 11 2023
Way of finding: Brute Force
0

n=3, a(3)=0
-

n=5, a(5)=0
Announcement: https://vk.com/wall162891802_2443, Eduard I. Vatutin, Jul 11 2023
Way of finding: Brute Force
0 1 2 3 4 
2 3 4 0 1 
4 0 1 2 3 
1 2 3 4 0 
3 4 0 1 2 

n=7, a(7)=0
Announcement: https://vk.com/wall162891802_2443, Eduard I. Vatutin, Jul 11 2023
Way of finding: Brute Force
0 1 2 3 4 5 6 
2 3 4 5 6 0 1 
4 5 6 0 1 2 3 
6 0 1 2 3 4 5 
1 2 3 4 5 6 0 
3 4 5 6 0 1 2 
5 6 0 1 2 3 4 

n=9, a(9)=0
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n=11, a(11)=0
Announcement: https://vk.com/wall162891802_2443, Eduard I. Vatutin, Jul 11 2023
Way of finding: Brute Force
0 1 2 3 4 5 6 7 8 9 10 
2 3 4 5 6 7 8 9 10 0 1 
4 5 6 7 8 9 10 0 1 2 3 
6 7 8 9 10 0 1 2 3 4 5 
8 9 10 0 1 2 3 4 5 6 7 
10 0 1 2 3 4 5 6 7 8 9 
1 2 3 4 5 6 7 8 9 10 0 
3 4 5 6 7 8 9 10 0 1 2 
5 6 7 8 9 10 0 1 2 3 4 
7 8 9 10 0 1 2 3 4 5 6 
9 10 0 1 2 3 4 5 6 7 8 

n=13, a(13)=156
Announcement: https://vk.com/wall162891802_2443, Eduard I. Vatutin, Jul 11 2023
Way of finding: Brute Force
0 1 2 3 4 5 6 7 8 9 10 11 12 
9 11 7 6 12 0 3 10 4 5 2 1 8 
5 2 8 4 10 9 11 12 1 0 3 6 7 
4 3 6 5 0 1 2 8 9 7 11 12 10 
1 0 12 10 3 11 7 6 5 2 4 8 9 
2 7 11 9 1 12 8 4 10 3 6 0 5 
3 6 4 8 2 7 9 5 0 1 12 10 11 
8 12 10 0 5 6 4 2 3 11 7 9 1 
7 5 9 1 11 3 10 0 6 12 8 4 2 
6 4 3 2 7 8 12 1 11 10 9 5 0 
11 10 0 12 6 4 5 9 7 8 1 2 3 
12 8 1 11 9 10 0 3 2 4 5 7 6 
10 9 5 7 8 2 1 11 12 6 0 3 4 

n=15, a(15)=0
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n=17, a(17)=272
Announcement: https://vk.com/wall162891802_2443, Eduard I. Vatutin, Jul 11 2023
Way of finding: Brute Force
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 
11 15 16 12 8 14 0 5 4 13 6 7 10 9 1 2 3 
8 10 3 11 9 13 2 15 0 14 1 5 4 7 6 16 12 
9 13 7 8 10 6 1 12 3 15 2 16 0 14 4 5 11 
10 6 1 4 13 7 5 16 9 8 3 12 11 15 2 14 0 
15 7 5 16 14 1 4 0 11 6 13 8 9 10 3 12 2 
12 3 4 0 11 2 16 14 15 10 5 1 13 6 7 8 9 
6 9 8 14 15 10 12 11 2 3 7 0 16 1 5 4 13 
1 5 6 13 2 3 7 9 10 12 8 4 15 11 16 0 14 
2 16 0 5 1 12 8 4 6 7 9 13 14 3 10 11 15 
3 12 11 15 0 16 9 13 14 5 4 6 1 2 8 7 10 
7 8 9 10 3 15 11 6 1 2 0 14 5 16 12 13 4 
14 4 13 6 7 8 3 10 5 16 12 15 2 0 11 9 1 
16 2 14 1 5 4 13 8 7 0 11 9 3 12 15 10 6 
5 11 12 2 16 0 14 1 13 4 15 10 6 8 9 3 7 
4 0 10 9 12 11 15 2 16 1 14 3 7 5 13 6 8 
13 14 15 7 6 9 10 3 12 11 16 2 8 4 0 1 5 

n=19, a(19)=342
Announcement: https://vk.com/wall162891802_2443, Eduard I. Vatutin, Jul 11 2023
Way of finding: Brute Force
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 
13 17 5 6 14 0 9 3 4 11 15 7 16 2 10 18 12 1 8 
11 10 8 9 3 18 17 15 14 0 16 12 4 1 6 7 13 2 5 
9 16 7 11 15 14 13 8 12 18 17 1 2 0 5 3 4 10 6 
3 15 1 4 16 12 18 10 11 2 13 8 5 6 17 9 14 0 7 
4 14 12 5 0 1 2 13 7 16 6 10 11 9 3 8 15 18 17 
8 0 18 2 9 17 5 6 10 4 1 3 7 16 15 14 11 12 13 
10 11 17 13 6 15 8 9 3 7 0 5 14 4 1 12 18 16 2 
6 7 16 8 10 3 12 11 15 14 4 17 9 18 0 5 2 13 1 
5 3 4 1 11 7 14 2 16 12 18 0 8 15 13 17 9 6 10 
7 9 14 0 5 16 4 18 6 1 2 13 17 11 12 10 8 15 3 
14 4 15 18 17 9 1 0 13 3 5 6 10 8 16 2 7 11 12 
2 18 0 12 13 8 15 5 17 10 14 9 3 7 11 1 6 4 16 
1 6 13 17 2 10 11 12 9 8 7 18 15 14 4 16 5 3 0 
17 5 3 10 8 6 7 16 2 15 11 4 13 12 18 0 1 9 14 
18 8 9 14 7 11 3 4 1 6 12 16 0 10 2 13 17 5 15 
12 13 11 15 18 4 16 14 0 5 3 2 1 17 7 6 10 8 9 
15 2 10 16 12 13 0 1 18 17 9 14 6 5 8 4 3 7 11 
16 12 6 7 1 2 10 17 5 13 8 15 18 3 9 11 0 14 4 

n=21, a(21)=0
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Jul 11 2023