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 | 0 |
| 2 | 2 |
| 3 | 7 |
| 4 | 25 |
| 5 | 91 |
| 6 | 330 |
| 7 | 1197 |
| 8 | 4342 |
| 9 | 15750 |
| 10 | 57131 |
| 11 | 207235 |
| 12 | 751717 |
| 13 | 2726752 |
| 14 | 9890925 |
| 15 | 35877996 |
| 16 | 130142590 |
| 17 | 472074687 |
| 18 | 1712387237 |
| 19 | 6211453675 |
| 20 | 22531210186 |
| 21 | 81728925145 |
| 22 | 296460649482 |
| 23 | 1075371008922 |
| 24 | 3900763250875 |
| 25 | 14149492419951 |