Number of Motzkin paths of length n with no UD, UHD, UHHD, UHHHD, ..., starting at level zero (here H=(1,0), U=(1,1), D=(1,-1)).

A089380

Number of Motzkin paths of length n with no UD, UHD, UHHD, UHHHD, ..., starting at level zero (here H=(1,0), U=(1,1), D=(1,-1)).

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =6a(6) =18a(7) =50a(8) =133a(9) =349a(10) =919a(11) =2443a(12) =6559a(13) =17759a(14) =48417a(15) =132765a(16) =365883a(17) =1012827a(18) =2814975a(19) =7852359a(20) =21977172a(21) =61697208a(22) =173688720a(23) =490222392a(24) =1386896799a(25) =3932313671a(26) =11172152779a(27) =31801604227a(28) =90683754826a(29) =259017103918

External references