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 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 13 |
| 5 | 51 |
| 6 | 197 |
| 7 | 828 |
| 8 | 3526 |
| 9 | 15538 |
| 10 | 69627 |
| 11 | 317564 |
| 12 | 1466868 |
| 13 | 6853320 |
| 14 | 32317354 |
| 15 | 153636769 |
| 16 | 735493374 |
| 17 | 3542610091 |
| 18 | 17155811156 |
| 19 | 83480667707 |
| 20 | 407969449010 |
| 21 | 2001479974330 |
| 22 | 9853652529076 |
| 23 | 48666276924852 |
| 24 | 241059431701113 |
| 25 | 1197237945360797 |
| 26 | 5960804381552300 |