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 | 45 |
| 3 | 1981 |
| 4 | 87165 |
| 5 | 3835261 |
| 6 | 168751485 |
| 7 | 7425065341 |
| 8 | 326702875005 |
| 9 | 14374926500221 |
| 10 | 632496766009725 |
| 11 | 27829857704427901 |
| 12 | 1224513738994827645 |
| 13 | 53878604515772416381 |
| 14 | 2370658598693986320765 |
| 15 | 104308978342535398113661 |
| 16 | 4589595047071557517001085 |
| 17 | 201942182071148530748047741 |