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 | 2 |
| 3 | 8 |
| 4 | 41 |
| 5 | 253 |
| 6 | 1858 |
| 7 | 15796 |
| 8 | 152219 |
| 9 | 1638323 |
| 10 | 19467494 |
| 11 | 252998224 |
| 12 | 3568259503 |
| 13 | 54263159347 |
| 14 | 884834059454 |
| 15 | 15397757661092 |
| 16 | 284767413357977 |
| 17 | 5576696746139689 |
| 18 | 115269732256964626 |
| 19 | 2507575465491619672 |
| 20 | 57262481225957071721 |
| 21 | 1369461739453440893261 |