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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.

A371777 a(n) = Sum_{k=0..floor(n/3)} binomial(2*n+2,n-3*k).

Table of values

n a(n)
0 1
1 4
2 15
3 57
4 220
5 858
6 3368
7 13276
8 52479
9 207861
10 824527
11 3274395
12 13015081
13 51769813
14 206045841
15 820475513
16 3268499356
17 13025237058
18 51922543076
19 207034128448
20 825713206746
21 3293865399518
22 13142007903586
23 52443095356218
24 209304385553096
25 835459642193284

List of values

[1, 4, 15, 57, 220, 858, 3368, 13276, 52479, 207861, 824527, 3274395, 13015081, 51769813, 206045841, 820475513, 3268499356, 13025237058, 51922543076, 207034128448, 825713206746, 3293865399518, 13142007903586, 52443095356218, 209304385553096, 835459642193284]

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

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