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 | 10 |
| 2 | 100 |
| 3 | 390 |
| 4 | 2090 |
| 5 | 9900 |
| 6 | 49130 |
| 7 | 239490 |
| 8 | 1175440 |
| 9 | 5754050 |
| 10 | 28195750 |
| 11 | 138110340 |
| 12 | 676601470 |
| 13 | 3314477450 |
| 14 | 16237031560 |
| 15 | 79541647910 |
| 16 | 389658289890 |
| 17 | 1908854053840 |
| 18 | 9351079145150 |
| 19 | 45808984336150 |
| 20 | 224408665354600 |
| 21 | 1099331244406030 |