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 | 1 |
| 3 | 7 |
| 4 | 37 |
| 5 | 201 |
| 6 | 1231 |
| 7 | 8653 |
| 8 | 69273 |
| 9 | 623521 |
| 10 | 6235291 |
| 11 | 68588301 |
| 12 | 823059733 |
| 13 | 10699776673 |
| 14 | 149796873591 |
| 15 | 2246953104061 |
| 16 | 35951249665201 |
| 17 | 611171244308673 |
| 18 | 11001082397556403 |
| 19 | 209020565553571981 |
| 20 | 4180411311071439981 |
| 21 | 87788637532500240001 |
| 22 | 1931350025715005280463 |