a(n) = 2*A132357(n).

Terms

a(0) =2a(1) =8a(2) =28a(3) =82a(4) =244a(5) =728a(6) =2186a(7) =6560a(8) =19684a(9) =59050a(10) =177148a(11) =531440a(12) =1594322a(13) =4782968a(14) =14348908a(15) =43046722a(16) =129140164a(17) =387420488a(18) =1162261466a(19) =3486784400a(20) =10460353204a(21) =31381059610a(22) =94143178828a(23) =282429536480a(24) =847288609442