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) |
|---|---|
| 1 | 0 |
| 2 | 4 |
| 3 | 14 |
| 4 | 68 |
| 5 | 303 |
| 6 | 1386 |
| 7 | 6311 |
| 8 | 28762 |
| 9 | 131012 |
| 10 | 596784 |
| 11 | 2718469 |
| 12 | 12383368 |
| 13 | 56409683 |
| 14 | 256961576 |
| 15 | 1170529586 |
| 16 | 5332078812 |
| 17 | 24289062227 |
| 18 | 110643256974 |
| 19 | 504010005519 |
| 20 | 2295902089838 |
| 21 | 10458455859448 |
| 22 | 47641099074536 |
| 23 | 217018109737881 |