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 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 15 |
| 5 | 45 |
| 6 | 105 |
| 7 | 225 |
| 8 | 405 |
| 9 | 495 |
| 10 | 1155 |
| 11 | 3675 |
| 12 | 4455 |
| 13 | 8085 |
| 14 | 19635 |
| 15 | 62475 |
| 16 | 75735 |
| 17 | 137445 |
| 18 | 373065 |
| 19 | 1187025 |
| 20 | 1741905 |
| 21 | 2611455 |
| 22 | 8580495 |
| 23 | 27301575 |
| 24 | 50515245 |
| 25 | 60063465 |
| 26 | 248834355 |
| 27 | 1021078905 |
| 28 | 2374216515 |
| 29 | 2822982855 |
| 30 | 11695214685 |
| 31 | 47990708535 |