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 | 3 |
| 2 | 20 |
| 3 | 201 |
| 4 | 2574 |
| 5 | 38740 |
| 6 | 654334 |
| 7 | 12050561 |
| 8 | 237383562 |
| 9 | 4935186778 |
| 10 | 107233505624 |
| 11 | 2417430607946 |
| 12 | 56224895607144 |
| 13 | 1343171657532430 |
| 14 | 32841495349026802 |
| 15 | 819503313717327041 |
| 16 | 20820095694805722362 |
| 17 | 537474654188020125882 |
| 18 | 14075078600122360679520 |
| 19 | 373373810133893669112710 |