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 | 2 |
| 2 | 5 |
| 3 | 18 |
| 4 | 88 |
| 5 | 489 |
| 6 | 3071 |
| 7 | 20667 |
| 8 | 146381 |
| 9 | 1072760 |
| 10 | 8071728 |
| 11 | 61990477 |
| 12 | 484182622 |
| 13 | 3835654678 |
| 14 | 30757242535 |
| 15 | 249255692801 |
| 16 | 2038827903834 |
| 17 | 16815060576958 |
| 18 | 139706974995635 |
| 19 | 1168468902294726 |
| 20 | 9831504782276593 |
| 21 | 83174244225508659 |
| 22 | 707159273362126228 |
| 23 | 6039827641569969225 |