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 | -3 |
| 2 | -7616 |
| 3 | -645084 |
| 4 | -14610432 |
| 5 | -171983600 |
| 6 | -1414609920 |
| 7 | -7628945436 |
| 8 | -27222867968 |
| 9 | -112609506987 |
| 10 | -386562553600 |
| 11 | -855436691900 |
| 12 | -2834434031616 |
| 13 | -6834860379504 |
| 14 | -16036772433920 |
| 15 | -33117544971900 |
| 16 | -69394306695168 |
| 17 | -89395660818176 |
| 18 | -249634755002304 |
| 19 | -352295159176476 |
| 20 | -768651312742400 |