a(n) = (1/2)*A357283(n).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =4a(6) =13a(7) =34a(8) =83a(9) =188a(10) =413a(11) =878a(12) =1839a(13) =3792a(14) =7761a(15) =15762a(16) =31891a(17) =64276a(18) =129301a(19) =259606a(20) =520727a(21) =1043480a(22) =2090009a(23) =4184090a(24) =8374299a(25) =16756764a(26) =33525789a(27) =67067934a(28) =134160415a(29) =268353568