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 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 29 |
| 5 | 205 |
| 6 | 1900 |
| 7 | 21592 |
| 8 | 289325 |
| 9 | 4456773 |
| 10 | 77512394 |
| 11 | 1501537750 |
| 12 | 32053808641 |
| 13 | 747561173689 |
| 14 | 18911411905052 |
| 15 | 515798244940224 |
| 16 | 15088848988966409 |
| 17 | 471291927943037785 |
| 18 | 15655172277281565058 |
| 19 | 551102758946418279862 |
| 20 | 20495154400760992784213 |
| 21 | 802951447375696586076213 |