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 | 33 |
| 5 | 198 |
| 6 | 1432 |
| 7 | 12136 |
| 8 | 117772 |
| 9 | 1287718 |
| 10 | 15658052 |
| 11 | 209568126 |
| 12 | 3061140398 |
| 13 | 48454548452 |
| 14 | 826155841924 |
| 15 | 15094511153752 |
| 16 | 294206836405288 |
| 17 | 6093273074402848 |
| 18 | 133628182522968752 |
| 19 | 3093469935389714928 |
| 20 | 75384936371166307872 |
| 21 | 1928960833317580172688 |