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 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 68 |
| 5 | 420 |
| 6 | 3015 |
| 7 | 24541 |
| 8 | 223884 |
| 9 | 2263381 |
| 10 | 25121075 |
| 11 | 303716281 |
| 12 | 3973432728 |
| 13 | 55931774473 |
| 14 | 842950049823 |
| 15 | 13543132571641 |
| 16 | 231076203767720 |
| 17 | 4172914800390601 |