2*n*(2*n+1)-(4+n)*(n-2)*N


19980*(2*n+3)*(2*n+1)*(n+2)*(n+1)+36*(2*n+3)*(n+2)*(5243*n^2-3198*n-29081)*N+(-5165349*n^4-79285914*n^3-417993231*n^2-931068234*n-752458032)*N^2+(-32242966*n^4-463513368*n^3-2389287842*n^2-5196107448*n-3955631976)*N^3+(-14085022*n^4-3416884*n^3+1783400374*n^2+11088652396*n+19231712496)*N^4+(120092728*n^4+2625383524*n^3+21532781936*n^2+78565716044*n+107669279208)*N^5+(22157632*n^4+623400032*n^3+6519761408*n^2+30028681792*n+51355297056)*N^6-384*(n+8)*(16027*n^3+340253*n^2+2363167*n+5335803)*N^7+145152*(n+5)*(n+9)*(n+8)*(2*n+19)*N^8

(Those are the operators annihilating our sequences a_1(n) and a_2(n) respectively. The second operator is not of minimal degree and it can be reduced to an operator of degree 4. For details, please refer to page 9 of the paper.)