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 | 25 |
| 3 | 195 |
| 4 | 1625 |
| 5 | 13879 |
| 6 | 120717 |
| 7 | 1063323 |
| 8 | 9454977 |
| 9 | 84688303 |
| 10 | 762972225 |
| 11 | 6906366907 |
| 12 | 62762167561 |
| 13 | 572251392039 |
| 14 | 5232480571761 |
| 15 | 47961608620959 |
| 16 | 440565328458621 |
| 17 | 4054586252967027 |
| 18 | 37377503512616413 |
| 19 | 345083448151227987 |
| 20 | 3190232694060946333 |
| 21 | 29529002023029712547 |