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 | 12 |
| 2 | 144 |
| 3 | 420 |
| 4 | 1225 |
| 5 | 7315 |
| 6 | 43681 |
| 7 | 175560 |
| 8 | 705600 |
| 9 | 3503640 |
| 10 | 17397241 |
| 11 | 76934095 |
| 12 | 340218025 |
| 13 | 1602280260 |
| 14 | 7546049424 |
| 15 | 34331884092 |
| 16 | 156198057961 |
| 17 | 724234470091 |
| 18 | 3358015935121 |
| 19 | 15408300507600 |
| 20 | 70701190560000 |
| 21 | 326286103743600 |