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 | 2 |
| 3 | 3 |
| 4 | 12 |
| 5 | 25 |
| 6 | 76 |
| 7 | 182 |
| 8 | 504 |
| 9 | 1275 |
| 10 | 3410 |
| 11 | 8811 |
| 12 | 23256 |
| 13 | 60580 |
| 14 | 159094 |
| 15 | 415715 |
| 16 | 1089648 |
| 17 | 2850645 |
| 18 | 7466468 |
| 19 | 19541994 |
| 20 | 51170460 |
| 21 | 133951675 |
| 22 | 350713222 |
| 23 | 918141623 |
| 24 | 2403786672 |
| 25 | 6293097000 |
| 26 | 16475700746 |
| 27 | 43133687427 |
| 28 | 112925875764 |