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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 5 |
| 6 | 20 |
| 7 | 84 |
| 8 | 316 |
| 9 | 1196 |
| 10 | 4461 |
| 11 | 16750 |
| 12 | 62878 |
| 13 | 237394 |
| 14 | 899265 |
| 15 | 3422111 |
| 16 | 13069026 |
| 17 | 50091095 |
| 18 | 192583152 |
| 19 | 742560511 |
| 20 | 2870523142 |
| 21 | 11122817672 |
| 22 | 43191285751 |
| 23 | 168046076423 |
| 24 | 654997492842 |
| 25 | 2557223459805 |
| 26 | 9999080270766 |
| 27 | 39152997087077 |
| 28 | 153511067364760 |