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 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 14 |
| 5 | 52 |
| 6 | 201 |
| 7 | 800 |
| 8 | 3260 |
| 9 | 13536 |
| 10 | 57068 |
| 11 | 243664 |
| 12 | 1051512 |
| 13 | 4579088 |
| 14 | 20097526 |
| 15 | 88810872 |
| 16 | 394811696 |
| 17 | 1764477304 |
| 18 | 7923087616 |
| 19 | 35728412152 |
| 20 | 161731039076 |
| 21 | 734646128920 |
| 22 | 3347600839252 |
| 23 | 15298276784648 |
| 24 | 70097391229500 |
| 25 | 321974115549256 |
| 26 | 1482242974320685 |