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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 5 |
| 6 | 10 |
| 7 | 35 |
| 8 | 70 |
| 9 | 216 |
| 10 | 567 |
| 11 | 2310 |
| 12 | 5775 |
| 13 | 21450 |
| 14 | 69498 |
| 15 | 243243 |
| 16 | 1153152 |
| 17 | 3620864 |
| 18 | 16336320 |
| 19 | 64664600 |
| 20 | 249420600 |
| 21 | 997682400 |
| 22 | 5462865408 |
| 23 | 21422145536 |