Second diagonal of A027517.

Terms

a(0) =7a(1) =19a(2) =49a(3) =1962a(4) =74100a(5) =100156a(6) =50911a(7) =25039a(8) =13189a(9) =111925a(10) =61425a(11) =172130400a(12) =15960298816a(13) =36469482889a(14) =21338706825a(15) =6300137600a(16) =7570610944a(17) =224166730176