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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 2 |
| 5 | 8 |
| 6 | 18 |
| 7 | 0 |
| 8 | 34 |
| 9 | 170 |
| 10 | 1643 |
| 11 | 3603 |
| 12 | 0 |
| 13 | 25118 |
| 14 | 139063 |
| 15 | 474559 |
| 16 | 284490 |
| 17 | 984006 |
| 18 | 6536387 |
| 19 | 24265729 |
| 20 | 18678366 |
| 21 | 96214018 |
| 22 | 277799290 |
| 23 | 1282283434 |
| 24 | 2077807072 |
| 25 | 1899874612 |
| 26 | 19252363859 |
| 27 | 44221482383 |
| 28 | 1967547352 |
| 29 | 29743945396 |
| 30 | 1265868622 |