cp's OEIS Frontend

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.

A027990 Sum{T(n,k)*T(n,2n-k)}, 0<=k<=n, T given by A027926.

Table of values

n a(n)
0 1
1 2
2 7
3 21
4 65
5 194
6 573
7 1668
8 4809
9 13745
10 39011
11 110052
12 308857
13 862886
14 2401195
15 6658509
16 18406373
17 50738918
18 139513269
19 382731240
20 1047768621
21 2862908777
22 7808872007
23 21265115976
24 57822787825
25 157010774474
26 425795804623

List of values

[1, 2, 7, 21, 65, 194, 573, 1668, 4809, 13745, 39011, 110052, 308857, 862886, 2401195, 6658509, 18406373, 50738918, 139513269, 382731240, 1047768621, 2862908777, 7808872007, 21265115976, 57822787825, 157010774474, 425795804623]