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 | 7 |
| 3 | 80 |
| 4 | 1119 |
| 5 | 17437 |
| 6 | 290532 |
| 7 | 5066364 |
| 8 | 91311055 |
| 9 | 1687341227 |
| 10 | 31797227631 |
| 11 | 608727899936 |
| 12 | 11805599569092 |
| 13 | 231454163924700 |
| 14 | 4579765707561240 |
| 15 | 91340133073920420 |
| 16 | 1834295500622405295 |
| 17 | 37059418988408887015 |
| 18 | 752741444501505866325 |
| 19 | 15362331852042084534240 |
| 20 | 314860558967057266779495 |