Number of lattice paths from (0,0) to (n,n) consisting of steps U=(1,1), H=(1,0) and S=(0,1) such that the first step leaving the diagonal (if any) is an H step.

A226994

Number of lattice paths from (0,0) to (n,n) consisting of steps U=(1,1), H=(1,0) and S=(0,1) such that the first step leaving the diagonal (if any) is an H step.

Terms

    a(0) =1a(1) =2a(2) =7a(3) =32a(4) =161a(5) =842a(6) =4495a(7) =24320a(8) =132865a(9) =731282a(10) =4048727a(11) =22523360a(12) =125797985a(13) =704966810a(14) =3961924127a(15) =22321190912a(16) =126027618305a(17) =712917362210

External references