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 | 153 |
| 4 | 1683 |
| 5 | 22698 |
| 6 | 362403 |
| 7 | 6683463 |
| 8 | 139787568 |
| 9 | 3269240883 |
| 10 | 84535585263 |
| 11 | 2394699999948 |
| 12 | 73749495626253 |
| 13 | 2453332830142743 |
| 14 | 87667856626175298 |
| 15 | 3349116499958627733 |
| 16 | 136209377351085310863 |
| 17 | 5875794769594996985778 |
| 18 | 267968680043585007829383 |