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 | 4 |
| 2 | 31 |
| 3 | 274 |
| 4 | 2461 |
| 5 | 22144 |
| 6 | 199291 |
| 7 | 1793614 |
| 8 | 16142521 |
| 9 | 145282684 |
| 10 | 1307544151 |
| 11 | 11767897354 |
| 12 | 105911076181 |
| 13 | 953199685624 |
| 14 | 8578797170611 |
| 15 | 77209174535494 |
| 16 | 694882570819441 |
| 17 | 6253943137374964 |
| 18 | 56285488236374671 |
| 19 | 506569394127372034 |