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 | 9 |
| 3 | 66 |
| 4 | 450 |
| 5 | 2955 |
| 6 | 18963 |
| 7 | 119812 |
| 8 | 748548 |
| 9 | 4637205 |
| 10 | 28537245 |
| 11 | 174683718 |
| 12 | 1064611782 |
| 13 | 6464582943 |
| 14 | 39132819495 |
| 15 | 236256182280 |
| 16 | 1423046656008 |
| 17 | 8554078990377 |
| 18 | 51327262010673 |
| 19 | 307488810131530 |
| 20 | 1839455028693450 |