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 | 6 |
| 2 | 21 |
| 3 | 56 |
| 4 | 126 |
| 5 | 252 |
| 6 | 461 |
| 7 | 780 |
| 8 | 1209 |
| 9 | 1638 |
| 10 | 1638 |
| 11 | 0 |
| 12 | -6187 |
| 13 | -23238 |
| 14 | -63783 |
| 15 | -151316 |
| 16 | -326382 |
| 17 | -652764 |
| 18 | -1217483 |
| 19 | -2107560 |
| 20 | -3322995 |
| 21 | -4538430 |
| 22 | -4538430 |
| 23 | 0 |
| 24 | 16942381 |
| 25 | 63239286 |
| 26 | 172791861 |
| 27 | 408855776 |
| 28 | 880983606 |
| 29 | 1761967212 |
| 30 | 3287837741 |
| 31 | 5694626340 |