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 | 2 |
| 2 | 4 |
| 3 | 14 |
| 4 | 57 |
| 5 | 312 |
| 6 | 2071 |
| 7 | 15030 |
| 8 | 117735 |
| 9 | 967850 |
| 10 | 8268816 |
| 11 | 72833730 |
| 12 | 658049140 |
| 13 | 6074058060 |
| 14 | 57106433817 |
| 15 | 545532037612 |
| 16 | 5284835906037 |
| 17 | 51833908183164 |
| 18 | 514019531037910 |
| 19 | 5147924676612282 |
| 20 | 52017438279806634 |
| 21 | 529867070532745464 |