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 | 17 |
| 4 | 74 |
| 5 | 395 |
| 6 | 2526 |
| 7 | 19087 |
| 8 | 168603 |
| 9 | 1723065 |
| 10 | 20148031 |
| 11 | 266437102 |
| 12 | 3938754720 |
| 13 | 64391209604 |
| 14 | 1152961464743 |
| 15 | 22424127879610 |
| 16 | 470399253269776 |
| 17 | 10579865622308851 |
| 18 | 253840801521314095 |
| 19 | 6468953273455413674 |
| 20 | 174452533187403980841 |
| 21 | 4962228907578051232358 |