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 | 5 |
| 2 | 40 |
| 3 | 364 |
| 4 | 2897 |
| 5 | 21369 |
| 6 | 148257 |
| 7 | 970246 |
| 8 | 6032341 |
| 9 | 35850410 |
| 10 | 204646488 |
| 11 | 1126463948 |
| 12 | 5999145787 |
| 13 | 30999381232 |
| 14 | 155798366059 |
| 15 | 763194776551 |
| 16 | 3650648583934 |
| 17 | 17079277343463 |
| 18 | 78262895082681 |
| 19 | 351708874155894 |
| 20 | 1551843168854346 |