OFFSET
0,3
EXAMPLE
a(3) = 420:
1 5 6
5 3 4
6 4 2
a(4) = 41451:
1 5 8 10
5 4 9 7
8 9 3 6
10 7 6 2
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Stefano Spezia, Feb 14 2022
EXTENSIONS
a(5)-a(6) from Hugo Pfoertner, Feb 15 2022
STATUS
approved