A340912 - OEIS

%I #4 Jan 28 2021 21:40:13

%S 1,1,6,63,907,16208,340458,8169034,220494839,6638599425,221835477385,

%T 8197807088637,333879685074774,14929308189076011,729701504761143784,

%U 38801435534565069687,2233844275229192069586,138592433800490757379259

%N Central terms of triangle A340910.

%o (PARI) {A340910(n, k) = my(A=1); for(i=1, n, A = sum(m=0, n, x^m/(1 - x*y*A^m +x*O(x^n))) ); polcoeff(polcoeff(A, n, x), k, y)}

%o for(n=0, 20, print1(A340910(2*n, n), ", "))

%o (PARI) {A340910(n, k) = my(A=1); for(i=1, n, A = sum(m=0, n, x^m*y^m/(1 - x*A^m +x*O(x^n))) ); polcoeff(polcoeff(A, n, x), k, y)}

%o for(n=0, 20, print1(A340910(2*n, n), ", "))

%K nonn

%O 0,3

%A _Paul D. Hanna_, Jan 28 2021