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 | 3 |
| 2 | 9 |
| 3 | 36 |
| 4 | 162 |
| 5 | 783 |
| 6 | 3969 |
| 7 | 20817 |
| 8 | 112023 |
| 9 | 615033 |
| 10 | 3431403 |
| 11 | 19398690 |
| 12 | 110880900 |
| 13 | 639730305 |
| 14 | 3720657807 |
| 15 | 21790419444 |
| 16 | 128398625658 |
| 17 | 760668489729 |
| 18 | 4528069760691 |
| 19 | 27070491820644 |
| 20 | 162464919528222 |
| 21 | 978463778897637 |