Number of n-step one-sided prudent walks, avoiding single west steps and single east steps.

Terms

a(0) =1a(1) =1a(2) =3a(3) =7a(4) =13a(5) =25a(6) =51a(7) =103a(8) =205a(9) =409a(10) =819a(11) =1639a(12) =3277a(13) =6553a(14) =13107a(15) =26215a(16) =52429a(17) =104857a(18) =209715a(19) =419431a(20) =838861a(21) =1677721a(22) =3355443a(23) =6710887a(24) =13421773a(25) =26843545a(26) =53687091a(27) =107374183a(28) =214748365a(29) =429496729