Number of up steps starting at an even 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.
A121523
Number of up steps starting at an even 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) =1a(1) =3a(2) =10a(3) =33a(4) =103a(5) =315a(6) =941a(7) =2770a(8) =8051a(9) =23171a(10) =66138a(11) =187486a(12) =528365a(13) =1481501a(14) =4135756a(15) =11500721a(16) =31871625a(17) =88054825a(18) =242609585a(19) =666783380a(20) =1828452021a(21) =5003697403a(22) =13667302500a(23) =37267071708a(24) =101455834153a(25) =275797332135
External references
- oeis: A121523