A014486-encoding of symmetric binary trees.

Terms

a(0) =0a(1) =2a(2) =50a(3) =844a(4) =906a(5) =13624a(6) =13876a(7) =14642a(8) =14892a(9) =15402a(10) =218352a(11) =219368a(12) =222436a(13) =223448a(14) =225492a(15) =234722a(16) =235730a(17) =238796a(18) =239800a(19) =241844a(20) =246986a(21) =247986a(22) =250028a(23) =254122a(24) =3494880a(25) =3498960a(26) =3511240a(27) =3515312a(28) =3523496a(29) =3560388