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 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 20 |
| 5 | 84 |
| 6 | 354 |
| 7 | 1540 |
| 8 | 6704 |
| 9 | 29610 |
| 10 | 131745 |
| 11 | 591049 |
| 12 | 2669346 |
| 13 | 12131148 |
| 14 | 55431285 |
| 15 | 254539897 |
| 16 | 1174027598 |
| 17 | 5436826110 |
| 18 | 25269402555 |
| 19 | 117838870833 |
| 20 | 551192276450 |
| 21 | 2585418254532 |
| 22 | 12158383558066 |
| 23 | 57313008207960 |