Number of permutations p of [n] such that 0p has a nonincreasing jump sequence beginning with ceiling(n/2).

A303204

Number of permutations p of [n] such that 0p has a nonincreasing jump sequence beginning with ceiling(n/2).

Terms

    a(0) =1a(1) =1a(2) =1a(3) =2a(4) =5a(5) =12a(6) =36a(7) =98a(8) =327a(9) =988a(10) =3392a(11) =10872a(12) =38795a(13) =129520a(14) =469662a(15) =1609176a(16) =5935728a(17) =20786804a(18) =77416352a(19) =274792342a(20) =1035050705a(21) =3719296036a(22) =14094000938a(23) =51119572738a(24) =195075365778a(25) =712918642042

External references