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 | 1 |
| 3 | 3 |
| 4 | 7 |
| 5 | 18 |
| 6 | 51 |
| 7 | 155 |
| 8 | 486 |
| 9 | 1555 |
| 10 | 5095 |
| 11 | 17038 |
| 12 | 57801 |
| 13 | 198471 |
| 14 | 689039 |
| 15 | 2415043 |
| 16 | 8534022 |
| 17 | 30375188 |
| 18 | 108815273 |
| 19 | 392076629 |
| 20 | 1420064031 |
| 21 | 5167575997 |
| 22 | 18885299641 |
| 23 | 69287981666 |
| 24 | 255121926519 |
| 25 | 942474271999 |
| 26 | 3492314839349 |
| 27 | 12977225566680 |
| 28 | 48349025154154 |