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 | 1 |
| 2 | 12 |
| 3 | 189 |
| 4 | 2808 |
| 5 | 42201 |
| 6 | 632772 |
| 7 | 9492309 |
| 8 | 142382448 |
| 9 | 2135743281 |
| 10 | 32036129532 |
| 11 | 480542002029 |
| 12 | 7208129853288 |
| 13 | 108121948330761 |
| 14 | 1621829223367092 |
| 15 | 24327438355289349 |
| 16 | 364911575314991328 |
| 17 | 5473673629767916641 |
| 18 | 82105104446389609452 |