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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 7 |
| 6 | 33 |
| 7 | 132 |
| 8 | 484 |
| 9 | 1684 |
| 10 | 5661 |
| 11 | 18579 |
| 12 | 59917 |
| 13 | 190696 |
| 14 | 600744 |
| 15 | 1877256 |
| 16 | 5828185 |
| 17 | 17998783 |
| 18 | 55342617 |
| 19 | 169552428 |
| 20 | 517884748 |
| 21 | 1577812060 |
| 22 | 4796682165 |
| 23 | 14555626635 |
| 24 | 44100374341 |
| 25 | 133436026192 |
| 26 | 403279293648 |
| 27 | 1217616622992 |
| 28 | 3673214880049 |
| 29 | 11072960931319 |