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 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 10 |
| 4 | 41 |
| 5 | 206 |
| 6 | 1237 |
| 7 | 8660 |
| 8 | 69281 |
| 9 | 623530 |
| 10 | 6235301 |
| 11 | 68588312 |
| 12 | 823059745 |
| 13 | 10699776686 |
| 14 | 149796873605 |
| 15 | 2246953104076 |
| 16 | 35951249665217 |
| 17 | 611171244308690 |
| 18 | 11001082397556421 |
| 19 | 209020565553572000 |
| 20 | 4180411311071440001 |
| 21 | 87788637532500240022 |