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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.

A182904 Number of weighted lattice paths in L_n having no peaks. The members of L_n are paths of weight n that start at (0,0), end on the horizontal axis and whose steps are of the following four kinds: an (1,0)-step with weight 1, an (1,0)-step with weight 2, a (1,1)-step with weight 2, and a (1,-1)-step with weight 1. The weight of a path is the sum of the weights of its steps. A peak is a (1,1)-step followed by a (1,-1)-step.

Table of values

n a(n)
0 1
1 1
2 2
3 4
4 9
5 21
6 48
7 112
8 263
9 623
10 1484
11 3550
12 8525
13 20537
14 49612
15 120136
16 291519
17 708699
18 1725714
19 4208364
20 10276173
21 25122829
22 61486180
23 150632012
24 369361757
25 906462529
26 2226297008
27 5471757126
28 13457326605
29 33117622245
30 81547372396

List of values

[1, 1, 2, 4, 9, 21, 48, 112, 263, 623, 1484, 3550, 8525, 20537, 49612, 120136, 291519, 708699, 1725714, 4208364, 10276173, 25122829, 61486180, 150632012, 369361757, 906462529, 2226297008, 5471757126, 13457326605, 33117622245, 81547372396]

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

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