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 | 132 |
| 2 | 4422 |
| 3 | 68772 |
| 4 | 643632 |
| 5 | 4197468 |
| 6 | 20934474 |
| 7 | 85014204 |
| 8 | 293744154 |
| 9 | 891454124 |
| 10 | 2432878866 |
| 11 | 6078578508 |
| 12 | 14097919968 |
| 13 | 30684132468 |
| 14 | 63221641758 |
| 15 | 124188986196 |
| 16 | 233931828834 |
| 17 | 424600608564 |
| 18 | 745616925614 |
| 19 | 1271112537684 |
| 20 | 2109875558208 |
| 21 | 3418440803052 |