a(n) is the total area of all closed Deutsch paths of length n.

Terms

a(0) =1a(1) =3a(2) =12a(3) =39a(4) =129a(5) =411a(6) =1300a(7) =4065a(8) =12633a(9) =39046a(10) =120204a(11) =368844a(12) =1128837a(13) =3447303a(14) =10508592a(15) =31985085a(16) =97226733a(17) =295214316a(18) =895502520a(19) =2714106318a(20) =8219809425a(21) =24877611798a(22) =75248738292a(23) =227488953354a(24) =687408882709