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 | 8 |
| 5 | 24 |
| 6 | 74 |
| 7 | 238 |
| 8 | 786 |
| 9 | 2646 |
| 10 | 9071 |
| 11 | 31536 |
| 12 | 110967 |
| 13 | 394420 |
| 14 | 1414053 |
| 15 | 5107523 |
| 16 | 18568628 |
| 17 | 67894564 |
| 18 | 249513890 |
| 19 | 921134164 |
| 20 | 3414439996 |
| 21 | 12703212213 |
| 22 | 47419589969 |
| 23 | 177551521838 |
| 24 | 666655929561 |
| 25 | 2509526456940 |
| 26 | 9469082269965 |
| 27 | 35807434636137 |
| 28 | 135681047696427 |