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 | 3 |
| 2 | 19 |
| 3 | 131 |
| 4 | 979 |
| 5 | 7683 |
| 6 | 62099 |
| 7 | 511619 |
| 8 | 4271699 |
| 9 | 36018179 |
| 10 | 305998099 |
| 11 | 2615234691 |
| 12 | 22459983059 |
| 13 | 193665818115 |
| 14 | 1675580699539 |
| 15 | 14538892408451 |
| 16 | 126467748738899 |
| 17 | 1102484411211779 |
| 18 | 9629327766561299 |
| 19 | 84247346901823619 |
| 20 | 738200425192338899 |
| 21 | 6477139329614712323 |