%I #7 Mar 30 2012 19:01:01
%S 1,2,10,55,351,2401,17248,128221,978082,7612155,60204488,482481220,
%T 3909460725,31974923487,263623879118,2188682538746,18282238300443,
%U 153537981720402,1295640515428649,10980400434511117,93418283866708579
%N Number of lattice paths from (0,0) to (n,n) using steps S={(k,0),(0,k),(r,r)|0<k<=2,0<r<=2} which never go above the line y=x.
%Y Cf. A175934, A175936, A175937, A175939
%K nonn
%O 0,2
%A _Eric Werley_, Dec 06 2010