a(n) is the number of Dyck paths of semilength n without height of peaks 0 (mod 3) and height of valleys 1 (mod 3).

A152172

a(n) is the number of Dyck paths of semilength n without height of peaks 0 (mod 3) and height of valleys 1 (mod 3).

Terms

    a(0) =1a(1) =1a(2) =2a(3) =3a(4) =6a(5) =12a(6) =26a(7) =59a(8) =138a(9) =332a(10) =814a(11) =2028a(12) =5118a(13) =13054a(14) =33598a(15) =87143a(16) =227542a(17) =597640a(18) =1577866a(19) =4185108a(20) =11146570a(21) =29798682a(22) =79932298a(23) =215072896a(24) =580327122a(25) =1569942098a(26) =4257254850a(27) =11569980794a(28) =31508150890a(29) =85968266198

External references