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 | 10 |
| 2 | 364 |
| 3 | 4664 |
| 4 | 40296 |
| 5 | 253072 |
| 6 | 1249768 |
| 7 | 5112544 |
| 8 | 17990600 |
| 9 | 56010096 |
| 10 | 157175032 |
| 11 | 403579328 |
| 12 | 959942664 |
| 13 | 2136701200 |
| 14 | 4488418616 |
| 15 | 8961185952 |
| 16 | 17105944648 |
| 17 | 31378295984 |
| 18 | 55549351800 |
| 19 | 95256535936 |
| 20 | 158727963272 |
| 21 | 257719103568 |