Triangle T(n,k) read by rows: the number of n X n {0,1} matrices with trace k where each row sum and each column sum is 2.
A284989
Triangle T(n,k) read by rows: the number of n X n {0,1} matrices with trace k where each row sum and each column sum is 2.
Terms
- a(0) =1a(1) =0a(2) =0a(3) =0a(4) =0a(5) =1a(6) =1a(7) =0a(8) =3a(9) =2a(10) =9a(11) =24a(12) =24a(13) =24a(14) =9a(15) =216a(16) =540a(17) =610a(18) =420a(19) =210a(20) =44a(21) =7570a(22) =18000a(23) =20175a(24) =13720a(25) =6300a(26) =1920a(27) =265a(28) =357435a(29) =829920
External references
- oeis: A284989