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 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 4 |
| 6 | 10 |
| 7 | 28 |
| 8 | 86 |
| 9 | 286 |
| 10 | 1019 |
| 11 | 3857 |
| 12 | 15418 |
| 13 | 64782 |
| 14 | 285041 |
| 15 | 1309355 |
| 16 | 6263085 |
| 17 | 31127475 |
| 18 | 160432093 |
| 19 | 856039863 |
| 20 | 4721638083 |
| 21 | 26883787141 |
| 22 | 157812750656 |
| 23 | 953995201996 |
| 24 | 5932516347277 |
| 25 | 37913110456751 |
| 26 | 248768719522450 |
| 27 | 1674488577654500 |
| 28 | 11553041105489900 |