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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 0 |
| 9 | 0 |
| 10 | 0 |
| 11 | 0 |
| 12 | 132 |
| 13 | 1716 |
| 14 | 12012 |
| 15 | 60060 |
| 16 | 240240 |
| 17 | 816816 |
| 18 | 2450448 |
| 19 | 6651216 |
| 20 | 16628040 |
| 21 | 38798760 |
| 22 | 85357272 |
| 23 | 178474296 |
| 24 | 356948592 |
| 25 | 686439600 |
| 26 | 1274816400 |
| 27 | 2294669520 |
| 28 | 4015671660 |
| 29 | 6850263420 |
| 30 | 11417105700 |
| 31 | 18627909300 |
| 32 | 29804654880 |
| 33 | 46835886240 |
| 34 | 72382733280 |
| 35 | 110147637600 |
| 36 | 165221456400 |
| 37 | 244527755472 |
| 38 | 357386719536 |
| 39 | 516225261552 |
| 40 | 737464659360 |