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 | 1 |
| 3 | 0 |
| 4 | 2 |
| 5 | 5 |
| 6 | 14 |
| 7 | 35 |
| 8 | 132 |
| 9 | 399 |
| 10 | 1556 |
| 11 | 5346 |
| 12 | 21515 |
| 13 | 82940 |
| 14 | 351298 |
| 15 | 1470859 |
| 16 | 6559568 |
| 17 | 29273847 |
| 18 | 137203616 |
| 19 | 647330760 |
| 20 | 3177545635 |
| 21 | 15754135608 |
| 22 | 80674471962 |
| 23 | 418173444944 |
| 24 | 2226807020143 |
| 25 | 12017943310050 |
| 26 | 66375955944554 |
| 27 | 371721782181000 |
| 28 | 2124422025178277 |