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 | 5 |
| 3 | 27 |
| 4 | 137 |
| 5 | 691 |
| 6 | 3465 |
| 7 | 17347 |
| 8 | 86777 |
| 9 | 433971 |
| 10 | 2170025 |
| 11 | 10850467 |
| 12 | 54253017 |
| 13 | 271266451 |
| 14 | 1356334985 |
| 15 | 6781680387 |
| 16 | 33908412857 |
| 17 | 169542086131 |
| 18 | 847710474345 |
| 19 | 4238552459107 |
| 20 | 21192762470297 |
| 21 | 105963812701011 |
| 22 | 529819064204105 |