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 | 3 |
| 2 | 15 |
| 3 | 99 |
| 4 | 783 |
| 5 | 7083 |
| 6 | 71415 |
| 7 | 789939 |
| 8 | 9485343 |
| 9 | 122721723 |
| 10 | 1701224775 |
| 11 | 25156450179 |
| 12 | 395362560303 |
| 13 | 6583219735563 |
| 14 | 115817825451735 |
| 15 | 2147443419579219 |
| 16 | 41868118883289663 |
| 17 | 856527397513863003 |
| 18 | 18350158259899381095 |
| 19 | 410942059850878349859 |
| 20 | 9603217302778609785423 |