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 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 17 |
| 5 | 79 |
| 6 | 453 |
| 7 | 3058 |
| 8 | 23698 |
| 9 | 207359 |
| 10 | 2021746 |
| 11 | 21733773 |
| 12 | 255371836 |
| 13 | 3255990905 |
| 14 | 44769874946 |
| 15 | 660355655454 |
| 16 | 10400601573397 |
| 17 | 174210076354396 |
| 18 | 3092228855290534 |
| 19 | 57979291036697519 |
| 20 | 1145090997974775999 |
| 21 | 23760638207976601980 |
| 22 | 516793881023491093070 |