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 | 3 |
| 3 | 12 |
| 4 | 53 |
| 5 | 244 |
| 6 | 1152 |
| 7 | 5531 |
| 8 | 26875 |
| 9 | 131760 |
| 10 | 650492 |
| 11 | 3229368 |
| 12 | 16105344 |
| 13 | 80624935 |
| 14 | 404913225 |
| 15 | 2039146908 |
| 16 | 10293657125 |
| 17 | 52071019600 |
| 18 | 263888886528 |
| 19 | 1339540863092 |
| 20 | 6809667715812 |
| 21 | 34663102092960 |
| 22 | 176655038497000 |
| 23 | 901269559693104 |