Number of double rises at an odd level in all nondecreasing Dyck paths of semilength n. A nondecreasing Dyck path is a Dyck path for which the sequence of the altitudes of the valleys is nondecreasing.
A121530
Number of double rises at an odd level in all nondecreasing Dyck paths of semilength n. A nondecreasing Dyck path is a Dyck path for which the sequence of the altitudes of the valleys is nondecreasing.
Terms
- a(0) =0a(1) =1a(2) =4a(3) =14a(4) =47a(5) =148a(6) =454a(7) =1359a(8) =4004a(9) =11644a(10) =33521a(11) =95696a(12) =271300a(13) =764605a(14) =2143964a(15) =5985186a(16) =16643779a(17) =46124692a(18) =127433562a(19) =351106955a(20) =964976460a(21) =2646158176a(22) =7241414949a(23) =19779499584a(24) =53933402472a(25) =146828245753a(26) =399137621524
External references
- oeis: A121530