OFFSET
1,2
COMMENTS
The seatings are maximal in the sense that no additional person can be seated without breaking the condition in name.
FORMULA
Conjecture: a(n) = (-7*a(n-1) - 7*a(n-2) + (n-2)*a(n-3) + 3*(n+1)*a(n-4) + 4*(n-1)*a(n-5) + 3*(n-3)*a(n-6) + (n-4)*a(n-7))/3 for n >= 9. - Pontus von Brömssen, Jun 23 2024
EXAMPLE
a(5)=7 since the seating arrangements in this case (where _ denotes an empty seat) are:
1 _ _ 2 _
1 _ _ _ 2
_ 1 _ _ 2
_ _ 1 _ _
2 _ _ 1 _
2 _ _ _ 1
_ 2 _ _ 1.
Notice the number of people seated is not always the same.
CROSSREFS
KEYWORD
nonn
AUTHOR
Enrique Navarrete, Jun 22 2024
EXTENSIONS
More terms from Pontus von Brömssen, Jun 23 2024
STATUS
approved