Index of first occurrence of n in A390514.

Terms

a(0) =1a(1) =5a(2) =24a(3) =82a(4) =272a(5) =471a(6) =15041a(7) =4746a(8) =120178a(9) =22165a(10) =88117a(11) =704941a(12) =14506580a(13) =2667568a(14) =100764071a(15) =108659164a(16) =215236225a(17) =8203821a(18) =724278033a(19) =213405375