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 | 18 |
| 3 | 135 |
| 4 | 1083 |
| 5 | 9219 |
| 6 | 80631 |
| 7 | 724080 |
| 8 | 6601639 |
| 9 | 61065270 |
| 10 | 570430258 |
| 11 | 5376309654 |
| 12 | 51020229343 |
| 13 | 487127706521 |
| 14 | 4674459993450 |
| 15 | 45056351087502 |
| 16 | 435965482847738 |
| 17 | 4232871507349381 |
| 18 | 41222355832803426 |
| 19 | 402540756184423291 |