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 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 2 |
| 5 | 11 |
| 6 | 62 |
| 7 | 406 |
| 8 | 3046 |
| 9 | 25737 |
| 10 | 242094 |
| 11 | 2510733 |
| 12 | 28473604 |
| 13 | 350651588 |
| 14 | 4661105036 |
| 15 | 66529260545 |
| 16 | 1014985068610 |
| 17 | 16484495344135 |
| 18 | 283989434253186 |
| 19 | 5173041992087562 |
| 20 | 99346991708245506 |
| 21 | 2006304350543326057 |
| 22 | 42505510227603678206 |
| 23 | 942678881135812883321 |