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) |
|---|---|
| 3 | 1 |
| 4 | 2 |
| 5 | 4 |
| 6 | 12 |
| 7 | 39 |
| 8 | 202 |
| 9 | 1219 |
| 10 | 9468 |
| 11 | 83435 |
| 12 | 836017 |
| 13 | 9223092 |
| 14 | 111255228 |
| 15 | 1453132944 |
| 16 | 20433309147 |
| 17 | 307690667072 |
| 18 | 4940118795869 |
| 19 | 84241805734539 |
| 20 | 1520564059349452 |
| 21 | 28963120073957838 |
| 22 | 580578894859915650 |
| 23 | 12217399235411398127 |
| 24 | 269291841184184374868 |
| 25 | 6204484017822892034404 |