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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.

A182889 Number of weighted lattice paths in L_n having no (1,0)-steps at level 0. 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.

Table of values

n a(n)
0 1
1 0
2 1
3 2
4 3
5 8
6 17
7 38
8 89
9 206
10 485
11 1152
12 2751
13 6614
14 15983
15 38798
16 94569
17 231342
18 567771
19 1397562
20 3449285
21 8533886
22 21161001
23 52579900
24 130896887
25 326440746
26 815437967
27 2040049514
28 5111051473
29 12822135138
30 32207384995
31 80995950182
32 203917464635

List of values

[1, 0, 1, 2, 3, 8, 17, 38, 89, 206, 485, 1152, 2751, 6614, 15983, 38798, 94569, 231342, 567771, 1397562, 3449285, 8533886, 21161001, 52579900, 130896887, 326440746, 815437967, 2040049514, 5111051473, 12822135138, 32207384995, 80995950182, 203917464635]

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

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