Number of valleys strictly above the x-axis in all hill-free Dyck paths of semilength n (a hill in a Dyck path is a peak at level 1).
A119012
Number of valleys strictly above the x-axis in all hill-free Dyck paths of semilength n (a hill in a Dyck path is a peak at level 1).
Terms
- a(0) =0a(1) =0a(2) =1a(3) =5a(4) =23a(5) =98a(6) =405a(7) =1644a(8) =6604a(9) =26356a(10) =104746a(11) =415155a(12) =1642493a(13) =6490622a(14) =25629581a(15) =101156936a(16) =399151400a(17) =1574818496a(18) =6213255614a(19) =24515233082a(20) =96739530062a(21) =381803092580
External references
- oeis: A119012