Number of nonnesting permutations of [n] avoiding 231 (and by symmetry 132, 213, or 312).
A383770
Number of nonnesting permutations of [n] avoiding 231 (and by symmetry 132, 213, or 312).
Terms
- a(0) =1a(1) =1a(2) =4a(3) =17a(4) =77a(5) =367a(6) =1815a(7) =9233a(8) =48014a(9) =254123a(10) =1364491a(11) =7414733a(12) =40701346a(13) =225359021a(14) =1257148285a(15) =7058816337a(16) =39863261170a(17) =226270553575
External references
- oeis: A383770