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.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 21 |
| 3 | 66 |
| 4 | 201 |
| 5 | 606 |
| 6 | 1821 |
| 7 | 5466 |
| 8 | 16401 |
| 9 | 49206 |
| 10 | 147621 |
| 11 | 442866 |
| 12 | 1328601 |
| 13 | 3985806 |
| 14 | 11957421 |
| 15 | 35872266 |
| 16 | 107616801 |
| 17 | 322850406 |
| 18 | 968551221 |
| 19 | 2905653666 |
| 20 | 8716961001 |
| 21 | 26150883006 |
| 22 | 78452649021 |
| 23 | 235357947066 |
| 24 | 706073841201 |
| 25 | 2118221523606 |