Number of permutations of [n] in which the length of every increasing run is 0 or 1 (mod 4).
A317111
Number of permutations of [n] in which the length of every increasing run is 0 or 1 (mod 4).
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =10a(6) =50a(7) =210a(8) =840a(9) =4200a(10) =29400a(11) =231000a(12) =1755600a(13) =13213200a(14) =109309200a(15) =1051050000a(16) =11099088000a(17) =120071952000
External references
- oeis: A317111