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 | 4 |
| 2 | 17 |
| 3 | 76 |
| 4 | 354 |
| 5 | 1704 |
| 6 | 8421 |
| 7 | 42508 |
| 8 | 218318 |
| 9 | 1137400 |
| 10 | 5996938 |
| 11 | 31940792 |
| 12 | 171605956 |
| 13 | 928931280 |
| 14 | 5061593709 |
| 15 | 27739833228 |
| 16 | 152809506582 |
| 17 | 845646470616 |
| 18 | 4699126915422 |
| 19 | 26209721959656 |
| 20 | 146681521121244 |
| 21 | 823429928805936 |