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 | 7 |
| 4 | 38 |
| 5 | 271 |
| 6 | 2342 |
| 7 | 23647 |
| 8 | 272918 |
| 9 | 3543631 |
| 10 | 51123782 |
| 11 | 811316287 |
| 12 | 14045783798 |
| 13 | 263429174191 |
| 14 | 5320671485222 |
| 15 | 115141595488927 |
| 16 | 2657827340990678 |
| 17 | 65185383514567951 |
| 18 | 1692767331628422662 |
| 19 | 46400793659664205567 |
| 20 | 1338843898122192101558 |
| 21 | 40562412499252036940911 |