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 | 4 |
| 4 | 14 |
| 5 | 44 |
| 6 | 131 |
| 7 | 376 |
| 8 | 1052 |
| 9 | 2888 |
| 10 | 7813 |
| 11 | 20892 |
| 12 | 55338 |
| 13 | 145428 |
| 14 | 379655 |
| 15 | 985520 |
| 16 | 2545720 |
| 17 | 6547792 |
| 18 | 16777993 |
| 19 | 42847988 |
| 20 | 109099078 |
| 21 | 277040572 |
| 22 | 701794187 |
| 23 | 1773851304 |
| 24 | 4474555476 |
| 25 | 11266301976 |
| 26 | 28318897549 |
| 27 | 71070913036 |
| 28 | 178106093666 |
| 29 | 445740656420 |
| 30 | 1114147888655 |