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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.

A105872 a(n) = Sum_{k=0..floor(n/3)} binomial(2*n-3*k, n).

Table of values

n a(n)
0 1
1 2
2 6
3 21
4 75
5 273
6 1009
7 3770
8 14202
9 53846
10 205216
11 785460
12 3017106
13 11624580
14 44905518
15 173863965
16 674506059
17 2621371005
18 10203609597
19 39773263035
20 155231706951
21 606554343495
22 2372544034143
23 9289131196485
24 36401388236461

List of values

[1, 2, 6, 21, 75, 273, 1009, 3770, 14202, 53846, 205216, 785460, 3017106, 11624580, 44905518, 173863965, 674506059, 2621371005, 10203609597, 39773263035, 155231706951, 606554343495, 2372544034143, 9289131196485, 36401388236461]

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

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