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 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 10 |
| 5 | 46 |
| 6 | 244 |
| 7 | 1481 |
| 8 | 10020 |
| 9 | 74400 |
| 10 | 599573 |
| 11 | 5200284 |
| 12 | 48223360 |
| 13 | 475557054 |
| 14 | 4965035754 |
| 15 | 54672110310 |
| 16 | 632853655686 |
| 17 | 7678552433184 |
| 18 | 97404631390960 |
| 19 | 1288861146261679 |
| 20 | 17752479062092470 |
| 21 | 254051633672160696 |
| 22 | 3770953046565933003 |
| 23 | 57964955567444706668 |