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 | 3 |
| 3 | 10 |
| 4 | 42 |
| 5 | 204 |
| 6 | 1127 |
| 7 | 6924 |
| 8 | 46704 |
| 9 | 342167 |
| 10 | 2700295 |
| 11 | 22799218 |
| 12 | 204799885 |
| 13 | 1947993126 |
| 14 | 19540680497 |
| 15 | 206001380039 |
| 16 | 2275381566909 |
| 17 | 26261810071925 |
| 18 | 315969045744894 |
| 19 | 3954454344433658 |
| 20 | 51382626410402336 |
| 21 | 691956435942841207 |