Number of permutations in S_n avoiding 21{bar 3}54 (i.e., every occurrence of 2154 is contained in an occurrence of a 21354) and such that the graph corresponding to the permutation is connected (see "Forest-like permutations" below).
A117107
Number of permutations in S_n avoiding 21{bar 3}54 (i.e., every occurrence of 2154 is contained in an occurrence of a 21354) and such that the graph corresponding to the permutation is connected (see "Forest-like permutations" below).
Terms
- a(0) =1a(1) =1a(2) =3a(3) =12a(4) =57a(5) =304a(6) =1765a(7) =10943a(8) =71519a(9) =488186a(10) =3456526a(11) =25251479a(12) =189545179
External references
- oeis: A117107