cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A121532 Number of double rises 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.

Table of values

n a(n)
1 0
2 0
3 1
4 6
5 24
6 87
7 290
8 926
9 2861
10 8640
11 25634
12 75015
13 217100
14 622620
15 1772097
16 5011394
17 14093980
18 39448623
19 109954398
20 305344314
21 845165725
22 2332485420
23 6420202246
24 17629525871
25 48304680504
26 132092031672
27 360557665825

List of values

[0, 0, 1, 6, 24, 87, 290, 926, 2861, 8640, 25634, 75015, 217100, 622620, 1772097, 5011394, 14093980, 39448623, 109954398, 305344314, 845165725, 2332485420, 6420202246, 17629525871, 48304680504, 132092031672, 360557665825]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.