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 | 3 |
| 4 | 16 |
| 5 | 112 |
| 6 | 1020 |
| 7 | 10222 |
| 8 | 109947 |
| 9 | 1230840 |
| 10 | 14218671 |
| 11 | 168256840 |
| 12 | 2031152928 |
| 13 | 24931793768 |
| 14 | 310420597116 |
| 15 | 3912823963482 |
| 16 | 49853370677834 |
| 17 | 641218583442360 |
| 18 | 8316918403772790 |
| 19 | 108686334145327785 |
| 20 | 1429927553582849256 |
| 21 | 18927697628428129728 |
| 22 | 251931892228273729375 |