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 | 2 |
| 2 | 11 |
| 3 | 64 |
| 4 | 417 |
| 5 | 2892 |
| 6 | 20941 |
| 7 | 156500 |
| 8 | 1198049 |
| 9 | 9346690 |
| 10 | 74042938 |
| 11 | 594001236 |
| 12 | 4815995027 |
| 13 | 39399831458 |
| 14 | 324840184326 |
| 15 | 2696343599336 |
| 16 | 22514057175337 |
| 17 | 188977375146888 |
| 18 | 1593661234493561 |
| 19 | 13495942411592260 |
| 20 | 114723671513478118 |
| 21 | 978570384358686064 |