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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.

A386617 a(n) = Sum_{k=0..n-1} binomial(3*k+1,k) * binomial(3*n-3*k,n-k-1).

Table of values

n a(n)
0 0
1 1
2 10
3 81
4 610
5 4436
6 31626
7 222681
8 1554772
9 10790721
10 74560728
11 513452604
12 3526463304
13 24168921568
14 165357919850
15 1129724254953
16 7709039995368
17 52551835079699
18 357930487932282
19 2436038623348521
20 16568626556643738
21 112626521811112464
22 765201654587796312
23 5196570956399432796

List of values

[0, 1, 10, 81, 610, 4436, 31626, 222681, 1554772, 10790721, 74560728, 513452604, 3526463304, 24168921568, 165357919850, 1129724254953, 7709039995368, 52551835079699, 357930487932282, 2436038623348521, 16568626556643738, 112626521811112464, 765201654587796312, 5196570956399432796]

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

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