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 | 2 |
| 3 | 9 |
| 4 | 54 |
| 5 | 412 |
| 6 | 3834 |
| 7 | 42131 |
| 8 | 533558 |
| 9 | 7645065 |
| 10 | 122177706 |
| 11 | 2153221318 |
| 12 | 41464853266 |
| 13 | 865908079369 |
| 14 | 19484990264956 |
| 15 | 469910189792853 |
| 16 | 12089047867952058 |
| 17 | 330423404118495975 |
| 18 | 9561012695542004496 |