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 | 9 |
| 3 | 69 |
| 4 | 513 |
| 5 | 3789 |
| 6 | 27945 |
| 7 | 206037 |
| 8 | 1518993 |
| 9 | 11198493 |
| 10 | 82558521 |
| 11 | 608644773 |
| 12 | 4487100705 |
| 13 | 33080169069 |
| 14 | 243876313161 |
| 15 | 1797924789621 |
| 16 | 13254807348657 |
| 17 | 97718168662461 |
| 18 | 720405829778265 |
| 19 | 5311034444054853 |
| 20 | 39154440039154497 |
| 21 | 288657547023732237 |
| 22 | 2128064642743736169 |