Number of contractible "tight" meanders of width n.

Terms

a(0) =1a(1) =2a(2) =6a(3) =14a(4) =34a(5) =68a(6) =150a(7) =296a(8) =586a(9) =1140a(10) =2182a(11) =4130a(12) =7678a(13) =14368a(14) =26068a(15) =48248a(16) =86572a(17) =158146a(18) =281410a(19) =509442a(20) =901014a(21) =1618544a(22) =2852464a(23) =5089580a(24) =8948694a(25) =15884762a(26) =27882762a(27) =49291952a(28) =86435358a(29) =152316976