A number triangle of lattice walks.

Terms

a(0) =1a(1) =2a(2) =1a(3) =5a(4) =5a(5) =1a(6) =14a(7) =20a(8) =8a(9) =1a(10) =42a(11) =75a(12) =44a(13) =11a(14) =1a(15) =132a(16) =275a(17) =208a(18) =77a(19) =14a(20) =1a(21) =429a(22) =1001a(23) =910a(24) =440a(25) =119a(26) =17a(27) =1a(28) =1430a(29) =3640