Number of permutations of 3 copies of 1..n with all adjacent differences <= 1 in absolute value.
A177291
Number of permutations of 3 copies of 1..n with all adjacent differences <= 1 in absolute value.
Terms
- a(0) =1a(1) =1a(2) =20a(3) =92a(4) =506a(5) =2288a(6) =10010a(7) =41618a(8) =168284a(9) =664958a(10) =2584442a(11) =9916688a(12) =37679618a(13) =142079906a(14) =532572428a(15) =1987037318a(16) =7386724082a(17) =27381500624a(18) =101272019258a(19) =373902595130
External references
- oeis: A177291