Number of Dyck paths with no UUU's and no DDD's, of semilength n and having no UDUD's (U=(1,1), D=(1,-1)).

A166289

Number of Dyck paths with no UUU's and no DDD's, of semilength n and having no UDUD's (U=(1,1), D=(1,-1)).

Terms

    a(0) =1a(1) =1a(2) =1a(3) =2a(4) =2a(5) =4a(6) =6a(7) =9a(8) =17a(9) =26a(10) =46a(11) =81a(12) =135a(13) =246a(14) =428a(15) =757a(16) =1373a(17) =2431a(18) =4411a(19) =7990a(20) =14434a(21) =26423a(22) =48137a(23) =88144a(24) =162086a(25) =297662a(26) =549342a(27) =1014677a(28) =1876551a(29) =3480596

External references