Number of uniquely solveable n X 2 nonograms (hanjie).

Terms

a(0) =1a(1) =4a(2) =14a(3) =52a(4) =210a(5) =816a(6) =3206a(7) =12536a(8) =48962a(9) =191226a(10) =746456a(11) =2913544a(12) =11371040a(13) =44376798a(14) =173181564a(15) =675834086a(16) =2637392942a(17) =10292179494a(18) =40164144690a(19) =156736057740a(20) =611644171812