# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a104544 Showing 1-1 of 1 %I A104544 #4 Mar 30 2012 17:36:01 %S A104544 1,1,1,3,0,1,5,3,0,1,11,6,3,0,1,25,13,9,3,0,1,55,40,16,12,3,0,1,129, %T A104544 95,60,20,15,3,0,1,303,250,155,80,25,18,3,0,1,721,661,415,235,100,31, %U A104544 21,3,0,1,1743,1708,1206,620,335,120,38,24,3,0,1,4241,4515,3262,1946,875,455 %N A104544 Triangle read by rows: T(n,k) is the number of Motzkin paths of length n having k HH's, where H=(1,0). %F A104544 G.f.=G=G(t, z) satisfies z^2(1+z-tz)G^2-(1-tz)G+1+z-tz=0. %e A104544 Triangle starts: %e A104544 1; %e A104544 1,1; %e A104544 3,0,1; %e A104544 5,3,0,1; %e A104544 11,6,3,0,1; %e A104544 T(4,1)=3 because we have HHUD, UDHH and UHHD, where U=(1,1), D=(1,-1) and H=(1,0). %Y A104544 Column 0 yields A104545. Row sums yield the Motzkin numbers (A001006). %K A104544 nonn,tabl %O A104544 1,4 %A A104544 _Emeric Deutsch_, Mar 14 2005 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE