%I #4 Sep 26 2012 04:24:38

%S 1,121,1762,20989,235543,2588641,28259704,308277688,3369314986,

%T 36937817182,406378312834,4487124168115,49722977591155,

%U 552884158181785,6167643983348920,69012419067802540,774413615153430670

%N Fourth diagonal (M=4) of triangle A115154 (called Y(3,1)).

%F a(n)= A115154(n+3,n+1), n>=0.

%F Recurrence: a(n)= b(n) - 9*(b(n-1)-b(n-2)), with b(n):=A064063(n+4), n>=0.

%F G.f.: ((-3+18*x+2*x^3) + 3*(1-9*x+9*x^2)*c(3*x))/((2+x)*x^3), with the o.g.f. c(x) of A000108 (Catalan).

%e a(0)= 1 = 190 - 9*(25-4); a(2) = 1762 = 14506 - 9*(1606-190).

%K nonn,easy

%O 0,2

%A _Wolfdieter Lang_, Feb 23 2006