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) |
|---|---|
| 2 | 1 |
| 3 | 8 |
| 4 | 70 |
| 5 | 560 |
| 6 | 4358 |
| 7 | 33160 |
| 8 | 248998 |
| 9 | 1851040 |
| 10 | 13655432 |
| 11 | 100126648 |
| 12 | 730548788 |
| 13 | 5308524968 |
| 14 | 38442000664 |
| 15 | 277565593032 |
| 16 | 1999068564026 |
| 17 | 14365917755936 |
| 18 | 103038218758426 |
| 19 | 737765745264544 |
| 20 | 5274413814993896 |
| 21 | 37655943519835560 |