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 | 12 |
| 4 | 56 |
| 5 | 280 |
| 6 | 1488 |
| 7 | 8232 |
| 8 | 47008 |
| 9 | 274824 |
| 10 | 1636520 |
| 11 | 9890584 |
| 12 | 60510480 |
| 13 | 374019776 |
| 14 | 2332131872 |
| 15 | 14651535840 |
| 16 | 92653845120 |
| 17 | 589317728376 |
| 18 | 3767523372432 |
| 19 | 24196006128592 |
| 20 | 156030800105840 |
| 21 | 1009911004804296 |
| 22 | 6558631830442384 |
| 23 | 42723991459518368 |
| 24 | 279091277437885920 |