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 | 5 |
| 2 | 12 |
| 3 | 38 |
| 4 | 130 |
| 5 | 462 |
| 6 | 1680 |
| 7 | 6204 |
| 8 | 23166 |
| 9 | 87230 |
| 10 | 330616 |
| 11 | 1259700 |
| 12 | 4820452 |
| 13 | 18513068 |
| 14 | 71318400 |
| 15 | 275467320 |
| 16 | 1066432950 |
| 17 | 4136847390 |
| 18 | 16075953960 |
| 19 | 62570669700 |
| 20 | 243882320220 |
| 21 | 951797460900 |
| 22 | 3718872587040 |
| 23 | 14545727618760 |