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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 20 |
| 6 | 72 |
| 7 | 274 |
| 8 | 1084 |
| 9 | 4413 |
| 10 | 18365 |
| 11 | 77773 |
| 12 | 334065 |
| 13 | 1451929 |
| 14 | 6373379 |
| 15 | 28214851 |
| 16 | 125826137 |
| 17 | 564736106 |
| 18 | 2549004457 |
| 19 | 11563003842 |
| 20 | 52688331678 |
| 21 | 241049183598 |
| 22 | 1106818411361 |
| 23 | 5098961600041 |
| 24 | 23561122837102 |
| 25 | 109171473224810 |
| 26 | 507136264223327 |
| 27 | 2361332083301582 |
| 28 | 11018704225690520 |
| 29 | 51520180227572593 |
| 30 | 241344269535483201 |
| 31 | 1132543412040153639 |
| 32 | 5323310040423904420 |
[1,1,2,6,20,72,274,1084,4413,18365,77773,334065, 1451929,6373379,28214851,125826137,564736106, 2549004457,11563003842,52688331678,241049183598, 1106818411361,5098961600041,23561122837102, 109171473224810,507136264223327,2361332083301582, 11018704225690520,51520180227572593, 241344269535483201,1132543412040153639, 5323310040423904420] |