1, 1, 2, 4, 9, 21, 56, 153, 431, 1269, 3748, 11283, 34892, 109201, 346671, 1113914, 3599997, 11754161, 38738445, 128543670, 429827021, 1444670782, 4879545858, 16575721093, 56568953256, 193962159926, 667744908521, 2306563486959, 7996271742308, 27813368946061, 97050437964778, 339653854810804, 1191781442742137