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 | 6 |
| 2 | 40 |
| 3 | 276 |
| 4 | 1924 |
| 5 | 13452 |
| 6 | 94132 |
| 7 | 658860 |
| 8 | 4611892 |
| 9 | 32282988 |
| 10 | 225980404 |
| 11 | 1581861804 |
| 12 | 11073030580 |
| 13 | 77511209964 |
| 14 | 542578461556 |
| 15 | 3798049214508 |
| 16 | 26586344468788 |
| 17 | 186104411215980 |
| 18 | 1302730878380788 |
| 19 | 9119116148403372 |