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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.

A287709 Number of Dyck paths of semilength n such that every peak at level y > 1 is preceded by (at least) one peak at level y-1.

Table of values

n a(n)
0 1
1 1
2 1
3 2
4 4
5 9
6 22
7 57
8 154
9 430
10 1234
11 3625
12 10865
13 33136
14 102598
15 321913
16 1021963
17 3278543
18 10617413
19 34678693
20 114151769
21 378436049
22 1262822229
23 4239469076
24 14312153289
25 48567846377
26 165610404277
27 567259571451
28 1951218773118
29 6738242931451
30 23356148951482

List of values

[1, 1, 1, 2, 4, 9, 22, 57, 154, 430, 1234, 3625, 10865, 33136, 102598, 321913, 1021963, 3278543, 10617413, 34678693, 114151769, 378436049, 1262822229, 4239469076, 14312153289, 48567846377, 165610404277, 567259571451, 1951218773118, 6738242931451, 23356148951482]

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

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