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 | 2 |
| 3 | 3 |
| 4 | 16 |
| 5 | 145 |
| 6 | 1536 |
| 7 | 19579 |
| 8 | 290816 |
| 9 | 4942305 |
| 10 | 94689280 |
| 11 | 2020278931 |
| 12 | 47523053568 |
| 13 | 1222147737265 |
| 14 | 34117226135552 |
| 15 | 1027550555918475 |
| 16 | 33213871550365696 |
| 17 | 1146891651823112641 |
| 18 | 42135941698113503232 |
| 19 | 1641164216596258397347 |
| 20 | 67550839668807638712320 |