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 | 19 |
| 4 | 109 |
| 5 | 881 |
| 6 | 7621 |
| 7 | 77785 |
| 8 | 854225 |
| 9 | 10750465 |
| 10 | 143737381 |
| 11 | 2121714761 |
| 12 | 33426065905 |
| 13 | 568250246305 |
| 14 | 10242445089605 |
| 15 | 197388381934801 |
| 16 | 4003553262384961 |
| 17 | 86010508861504385 |
| 18 | 1939950117886565125 |