a(n) is the smallest k such that A319447(k) = n.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =18a(5) =56a(6) =126a(7) =630a(8) =1638a(9) =8190a(10) =31122a(11) =155610a(12) =964782a(13) =4823910a(14) =35696934a(15) =178484670a(16) =1534968162a(17) =7674840810a(18) =84423248910a(19) =468165289410