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 | 15 |
| 3 | 27 |
| 4 | 255 |
| 5 | 703 |
| 6 | 1819 |
| 7 | 9663 |
| 8 | 26623 |
| 9 | 77671 |
| 10 | 159487 |
| 11 | 1212415 |
| 12 | 4637979 |
| 13 | 6631675 |
| 14 | 19638399 |
| 15 | 80049391 |
| 16 | 319804831 |
| 17 | 319804831 |
| 18 | 319804831 |
| 19 | 8528817511 |
| 20 | 59436135663 |
| 21 | 231913730799 |
| 22 | 272025660543 |
| 23 | 871673828443 |
| 24 | 3716509988199 |
| 25 | 3716509988199 |
| 26 | 3716509988199 |