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 | 5 |
| 3 | 18 |
| 4 | 94 |
| 5 | 472 |
| 6 | 2519 |
| 7 | 13694 |
| 8 | 76251 |
| 9 | 431488 |
| 10 | 2477726 |
| 11 | 14399942 |
| 12 | 84570550 |
| 13 | 501197804 |
| 14 | 2994043007 |
| 15 | 18012040166 |
| 16 | 109041492241 |
| 17 | 663838548026 |
| 18 | 4061954970953 |
| 19 | 24969125105686 |
| 20 | 154130498547414 |
| 21 | 955070091156516 |