a(n) is the number of Dyck paths of length n without height of peaks 1 (mod 3) and height of valleys 2 (mod 3).

A152173

a(n) is the number of Dyck paths of length n without height of peaks 1 (mod 3) and height of valleys 2 (mod 3).

Terms

    a(0) =1a(1) =0a(2) =1a(3) =2a(4) =4a(5) =10a(6) =23a(7) =56a(8) =138a(9) =344a(10) =870a(11) =2220a(12) =5716a(13) =14828a(14) =38717a(15) =101682a(16) =268416a(17) =711810a(18) =1895432a(19) =5066030a(20) =13586082a(21) =36547534a(22) =98593064a(23) =266661162a(24) =722953814a(25) =1964358938a(26) =5348367006a(27) =14589803090a(28) =39870312218a(29) =109136843138

External references