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 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 50 |
| 5 | 311 |
| 6 | 2072 |
| 7 | 14460 |
| 8 | 104346 |
| 9 | 772255 |
| 10 | 5829538 |
| 11 | 44710705 |
| 12 | 347424376 |
| 13 | 2729299748 |
| 14 | 21640457360 |
| 15 | 172957598120 |
| 16 | 1391926695402 |
| 17 | 11270059892943 |
| 18 | 91740990170150 |
| 19 | 750364940281275 |
| 20 | 6163650579487170 |
| 21 | 50824871829196575 |