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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 19 |
| 4 | 66 |
| 5 | 245 |
| 6 | 948 |
| 7 | 3791 |
| 8 | 15476 |
| 9 | 64402 |
| 10 | 272700 |
| 11 | 1171314 |
| 12 | 5090997 |
| 13 | 22334327 |
| 14 | 98802899 |
| 15 | 440488059 |
| 16 | 1977476043 |
| 17 | 8931332628 |
| 18 | 40548362135 |
| 19 | 184956945997 |
| 20 | 847373416171 |
| 21 | 3897973137387 |
| 22 | 17996663755917 |
| 23 | 83361921555277 |
| 24 | 387303463238708 |
| 25 | 1804529801429929 |
| 26 | 8430001295617115 |
| 27 | 39477866487103539 |
[1,2,6,19,66,245,948,3791,15476,64402,272700, 1171314,5090997,22334327,98802899,440488059, 1977476043,8931332628,40548362135,184956945997, 847373416171,3897973137387,17996663755917, 83361921555277,387303463238708,1804529801429929, 8430001295617115,39477866487103539] |