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 | 6 |
| 4 | 41 |
| 5 | 365 |
| 6 | 3984 |
| 7 | 51499 |
| 8 | 769159 |
| 9 | 13031514 |
| 10 | 246925295 |
| 11 | 5173842311 |
| 12 | 118776068256 |
| 13 | 2964697094281 |
| 14 | 79937923931761 |
| 15 | 2315462770608870 |
| 16 | 71705109685449689 |
| 17 | 2364107330976587909 |
| 18 | 82676528225908987824 |
| 19 | 3056806370495613000259 |
| 20 | 119137361202296994159415 |