OFFSET
1,4
LINKS
Andy Huchala, Illustration for n = 52.
Andy Huchala, Python program.
Math StackExchange, Black queens on n X n board, 2022.
FORMULA
Conjecture: a(5k)=4k-1, a(5k+1)=4k, a(5k+2)=4k+1, a(5k+3)=4k+1, a(5k+4)=4k+2. [This does not hold for n = 52 and n = 57. - Andy Huchala, Apr 02 2024]
a(n) = A053757(n-1), at least for 1 <= n <= 12. [This is unlikely to continue. - N. J. A. Sloane, Mar 11 2022] [Indeed the equality does not hold for n=13. - Martin Ehrenstein, Mar 11 2022]
a(n+1) >= a(n); a(2n) = A352426(2n). - Martin Ehrenstein, Mar 23 2022
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
George Baloglou, Mar 09 2022
EXTENSIONS
a(13)-a(26) from Martin Ehrenstein, Mar 11 2022
a(27)-a(28) from Martin Ehrenstein, Mar 15 2022
a(29)-a(30) from Martin Ehrenstein, Mar 23 2022
a(31)-a(60) from Andy Huchala, Mar 27 2024
STATUS
approved