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 | 5 |
| 3 | 25 |
| 4 | 173 |
| 5 | 1441 |
| 6 | 14165 |
| 7 | 160105 |
| 8 | 2044733 |
| 9 | 29105521 |
| 10 | 456781925 |
| 11 | 7834208185 |
| 12 | 145760370893 |
| 13 | 2923764916801 |
| 14 | 62891469229685 |
| 15 | 1444055265984265 |
| 16 | 35250519098274653 |
| 17 | 911569049328779281 |
| 18 | 24893164161460525445 |
| 19 | 715822742720760256345 |
| 20 | 21620050147748210572013 |