a(n) = A123610(2*n+2,n).

Terms

a(0) =1a(1) =4a(2) =39a(3) =392a(4) =4420a(5) =52272a(6) =644231a(7) =8179600a(8) =106376580a(9) =1410528080a(10) =19006875580a(11) =259613952864