Number of Colombian variant Langford pairings (solutions to Langford problem such that exactly one instance of {1, 2, 3, ..., n-2, n} occurs between the two instances of n-1), up to reversal of the order.
A336747
Number of Colombian variant Langford pairings (solutions to Langford problem such that exactly one instance of {1, 2, 3, ..., n-2, n} occurs between the two instances of n-1), up to reversal of the order.
Terms
- a(0) =0a(1) =0a(2) =1a(3) =1a(4) =0a(5) =0a(6) =3a(7) =10a(8) =0a(9) =0a(10) =76a(11) =140a(12) =0a(13) =0a(14) =2478a(15) =5454a(16) =0a(17) =0a(18) =105704a(19) =267312a(20) =0a(21) =0a(22) =7235244a(23) =25244832a(24) =0a(25) =0a(26) =709868768a(27) =2310292004a(28) =0a(29) =0
External references
- oeis: A336747