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 | 0 |
| 2 | 1 |
| 3 | 0 |
| 4 | 4 |
| 5 | 4 |
| 6 | 18 |
| 7 | 26 |
| 8 | 86 |
| 9 | 158 |
| 10 | 462 |
| 11 | 976 |
| 12 | 2665 |
| 13 | 6082 |
| 14 | 16040 |
| 15 | 38338 |
| 16 | 99536 |
| 17 | 244880 |
| 18 | 631923 |
| 19 | 1583796 |
| 20 | 4081939 |
| 21 | 10358670 |
| 22 | 26728731 |
| 23 | 68425494 |
| 24 | 176964795 |
| 25 | 455967376 |
| 26 | 1182454137 |
| 27 | 3061954102 |
| 28 | 7962768190 |
| 29 | 20702327552 |
| 30 | 53983118006 |
| 31 | 140817757006 |