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) |
|---|---|
| 1 | 21 |
| 2 | 271 |
| 3 | 2731 |
| 4 | 23351 |
| 5 | 176851 |
| 6 | 1225631 |
| 7 | 8006491 |
| 8 | 50556551 |
| 9 | 313882531 |
| 10 | 1932641711 |
| 11 | 11839990891 |
| 12 | 72260648471 |
| 13 | 439667406451 |
| 14 | 2668522016831 |
| 15 | 16163719991611 |
| 16 | 97745259402791 |
| 17 | 590286253682371 |
| 18 | 3560791008422351 |
| 19 | 21460113482174731 |