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 | 3 |
| 3 | 21 |
| 4 | 269 |
| 5 | 5501 |
| 6 | 164871 |
| 7 | 6826353 |
| 8 | 373877161 |
| 9 | 26202082729 |
| 10 | 2288805048251 |
| 11 | 243958190401341 |
| 12 | 31176599353144853 |
| 13 | 4706999020319020101 |
| 14 | 829102910675624591839 |
| 15 | 168548158717259440652601 |
| 16 | 39174415082612704149839761 |
| 17 | 10324151597447856368055425553 |
| 18 | 3062691062053211798175516784691 |