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 | 3 |
| 5 | 9 |
| 6 | 25 |
| 7 | 67 |
| 8 | 177 |
| 9 | 464 |
| 10 | 1216 |
| 11 | 3184 |
| 12 | 8336 |
| 13 | 21824 |
| 14 | 57136 |
| 15 | 149585 |
| 16 | 391619 |
| 17 | 1025273 |
| 18 | 2684201 |
| 19 | 7027331 |
| 20 | 18397793 |
| 21 | 48166048 |
| 22 | 126100352 |
| 23 | 330135008 |
| 24 | 864304672 |
| 25 | 2262779008 |
| 26 | 5924032352 |
| 27 | 15509318049 |
| 28 | 40603921795 |
| 29 | 106302447337 |
| 30 | 278303420217 |