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 | 1 |
| 2 | 3 |
| 3 | 21 |
| 4 | 190 |
| 5 | 2112 |
| 6 | 26922 |
| 7 | 382110 |
| 8 | 5920788 |
| 9 | 98862273 |
| 10 | 1762572957 |
| 11 | 33325846461 |
| 12 | 664774457583 |
| 13 | 13932829786025 |
| 14 | 305788481726799 |
| 15 | 7008171327166869 |
| 16 | 167321925537782445 |
| 17 | 4153009604547937170 |
| 18 | 106963758805117459392 |
| 19 | 2854029374011293902121 |
| 20 | 78773444214057182702790 |