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 | 1 |
| 3 | 5 |
| 4 | 17 |
| 5 | 51 |
| 6 | 149 |
| 7 | 439 |
| 8 | 1309 |
| 9 | 3927 |
| 10 | 11797 |
| 11 | 35423 |
| 12 | 106301 |
| 13 | 318903 |
| 14 | 956645 |
| 15 | 2869807 |
| 16 | 8609293 |
| 17 | 25827879 |
| 18 | 77483893 |
| 19 | 232452191 |
| 20 | 697357085 |
| 21 | 2092071255 |
| 22 | 6276212741 |
| 23 | 18828636175 |
| 24 | 56485906477 |
| 25 | 169457719431 |
| 26 | 508373162389 |
| 27 | 1525119495359 |
| 28 | 4575358494269 |
| 29 | 13726075482807 |