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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 3 |
| 6 | 14 |
| 7 | 38 |
| 8 | 125 |
| 9 | 360 |
| 10 | 1107 |
| 11 | 3297 |
| 12 | 10292 |
| 13 | 32134 |
| 14 | 103759 |
| 15 | 340566 |
| 16 | 1148150 |
| 17 | 3951339 |
| 18 | 13925330 |
| 19 | 50122316 |
| 20 | 184365292 |
| 21 | 692145409 |
| 22 | 2651444318 |
| 23 | 10356184440 |
| 24 | 41224744182 |
| 25 | 167150406897 |
| 26 | 689998967755 |
| 27 | 2898493498253 |
| 28 | 12384852601731 |
| 29 | 53804601888559 |
| 30 | 237566072006014 |