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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 5 |
| 5 | 18 |
| 6 | 59 |
| 7 | 185 |
| 8 | 564 |
| 9 | 1685 |
| 10 | 4957 |
| 11 | 14406 |
| 12 | 41455 |
| 13 | 118321 |
| 14 | 335400 |
| 15 | 945193 |
| 16 | 2650229 |
| 17 | 7398330 |
| 18 | 20573219 |
| 19 | 57013865 |
| 20 | 157517532 |
| 21 | 433993661 |
| 22 | 1192779085 |
| 23 | 3270835566 |
| 24 | 8950887895 |
| 25 | 24448816993 |
| 26 | 66665369424 |
| 27 | 181489721425 |
| 28 | 493361278949 |