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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.

A317782 Number of 2n-step paths from (0,0) to (0,n) that stay in the first quadrant (but may touch the axes) consisting of steps (1,0), (0,1), (0,-1) and (-1,1).

Table of values

n a(n)
0 1
1 1
2 5
3 51
4 474
5 4329
6 43406
7 469565
8 5228459
9 59259957
10 686003702
11 8097484169
12 97005128492
13 1175916181703
14 14404685872773
15 178105648065109
16 2220134252592683
17 27872257776993240
18 352143374331177766
19 4474477933645201621
20 57147423819800882972

List of values

[1, 1, 5, 51, 474, 4329, 43406, 469565, 5228459, 59259957, 686003702, 8097484169, 97005128492, 1175916181703, 14404685872773, 178105648065109, 2220134252592683, 27872257776993240, 352143374331177766, 4474477933645201621, 57147423819800882972]

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

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