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 | 11 |
| 3 | 51 |
| 4 | 275 |
| 5 | 1619 |
| 6 | 10067 |
| 7 | 64979 |
| 8 | 431059 |
| 9 | 2920403 |
| 10 | 20119507 |
| 11 | 140513235 |
| 12 | 992530387 |
| 13 | 7078367187 |
| 14 | 50896392147 |
| 15 | 368577073107 |
| 16 | 2685777334227 |
| 17 | 19678579249107 |
| 18 | 144888698621907 |
| 19 | 1071443581980627 |
| 20 | 7954422715502547 |