Number of length n left factors of Dyck paths having no base pyramids.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =6a(6) =11a(7) =21a(8) =40a(9) =76a(10) =146a(11) =279a(12) =539a(13) =1036a(14) =2011a(15) =3883a(16) =7566a(17) =14662a(18) =28654a(19) =55692a(20) =109098a(21) =212564a(22) =417210a(23) =814568a(24) =1601366a(25) =3132078a(26) =6165732a(27) =12077905a(28) =23803827a(29) =46691096