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 | 1 |
| 2 | 5 |
| 3 | 29 |
| 4 | 186 |
| 5 | 1374 |
| 6 | 11352 |
| 7 | 105048 |
| 8 | 1070640 |
| 9 | 11978640 |
| 10 | 145558080 |
| 11 | 1914027840 |
| 12 | 27035890560 |
| 13 | 408891369600 |
| 14 | 6585851059200 |
| 15 | 112656894336000 |
| 16 | 2038285492992000 |
| 17 | 38915729475840000 |
| 18 | 781515776369664000 |
| 19 | 16475855040820224000 |
| 20 | 363685261902133248000 |
| 21 | 8391522945839007744000 |