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 | 4 |
| 3 | 6 |
| 4 | 44 |
| 5 | 120 |
| 6 | 610 |
| 7 | 2114 |
| 8 | 9468 |
| 9 | 36384 |
| 10 | 155644 |
| 11 | 626450 |
| 12 | 2638994 |
| 13 | 10856924 |
| 14 | 45565118 |
| 15 | 189579786 |
| 16 | 796023260 |
| 17 | 3333362040 |
| 18 | 14022032560 |
| 19 | 58960463548 |
| 20 | 248542728364 |
| 21 | 1048148750060 |
| 22 | 4427187324102 |
| 23 | 18712146312998 |
| 24 | 79177190666034 |
| 25 | 335259593600120 |
| 26 | 1420797366753600 |