Number of permutations of 0..floor((3*n-1)/2) on even squares of an 3*n array such that each row, column, diagonal and (downwards) antidiagonal of even squares is increasing.
A215789
Number of permutations of 0..floor((3*n-1)/2) on even squares of an 3*n array such that each row, column, diagonal and (downwards) antidiagonal of even squares is increasing.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =2a(4) =5a(5) =12a(6) =42a(7) =110a(8) =462a(9) =1274a(10) =6006a(11) =17136a(12) =87516a(13) =255816a(14) =1385670a(15) =4124406a(16) =23371634a(17) =70549050a(18) =414315330a(19) =1264752060a(20) =7646001090a(21) =23555382240a(22) =145862174640a(23) =452806924752
External references
- oeis: A215789