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 | 1 |
| 4 | 5 |
| 5 | 19 |
| 6 | 64 |
| 7 | 202 |
| 8 | 612 |
| 9 | 1803 |
| 10 | 5206 |
| 11 | 14809 |
| 12 | 41650 |
| 13 | 116114 |
| 14 | 321478 |
| 15 | 885169 |
| 16 | 2426462 |
| 17 | 6627499 |
| 18 | 18048088 |
| 19 | 49026874 |
| 20 | 132901176 |
| 21 | 359625015 |
| 22 | 971639014 |
| 23 | 2621683741 |
| 24 | 7065545950 |
| 25 | 19022080034 |
| 26 | 51163908874 |
| 27 | 137499581917 |
| 28 | 369235213742 |
| 29 | 990822728623 |
| 30 | 2657069356996 |