There all together, 7, different equivalence classes For the equivalence class of patterns, {{[1, 2, 3, 4]}, {[4, 3, 2, 1]}} the member , {[1, 2, 3, 4]}, has a scheme of depth , 4 here it is: {[[], {}, {}], [[1], {}, {}], [[1, 2, 3], {[0, 0, 0, 1]}, {3}], [[2, 1], {}, {1}], [[2, 3, 1, 4], {[0, 0, 0, 0, 1]}, {4}], [[1, 3, 2], {}, {2}], [[2, 4, 1, 3], {}, {1, 2}], [[1, 2], {}, {}], [[2, 3, 1], {}, {}], [[3, 4, 1, 2], {}, {1, 2}], [[3, 4, 2, 1], {}, {3}]} Using the scheme, the first, , 31, terms are [1, 1, 2, 6, 23, 103, 513, 2761, 15767, 94359, 586590, 3763290, 24792705, 167078577, 1148208090, 8026793118, 56963722223, 409687815151, 2981863943718, 21937062144834, 162958355218089, 1221225517285209, 9225729232653663, 70209849031116183, 537935616492552297, 4147342550996290153, 32159907636432567578, 250717538500344886206, 1964347085978431234383, 15462159345628498316319, 122238900487877503161969] This enumerating sequence seems to have the 2 2 9 (n + 1) (41 + 42 n + 10 n ) N 2 annihilating operator , ---------- - --------------------- + N 2 2 (n + 4) (n + 4) For the equivalence class of patterns, {{[1, 2, 4, 3]}, {[2, 1, 3, 4]}, {[3, 4, 2, 1]}, {[4, 3, 1, 2]}} the member , {[1, 2, 4, 3]}, has a scheme of depth , 4 here it is: {[[], {}, {}], [[1], {}, {}], [[2, 1], {}, {1}], [[1, 3, 2], {}, {2}], [[2, 4, 1, 3], {}, {1, 2}], [[1, 2], {}, {}], [[2, 3, 1], {}, {}], [[3, 4, 1, 2], {}, {1, 2}], [[3, 4, 2, 1], {}, {3}], [[1, 2, 3], {[0, 0, 1, 0]}, {2}], [[2, 3, 1, 4], {[0, 0, 0, 1, 0]}, {4}]} Using the scheme, the first, , 31, terms are [1, 1, 2, 6, 23, 103, 513, 2761, 15767, 94359, 586590, 3763290, 24792705, 167078577, 1148208090, 8026793118, 56963722223, 409687815151, 2981863943718, 21937062144834, 162958355218089, 1221225517285209, 9225729232653663, 70209849031116183, 537935616492552297, 4147342550996290153, 32159907636432567578, 250717538500344886206, 1964347085978431234383, 15462159345628498316319, 122238900487877503161969] This enumerating sequence seems to have the 2 2 9 (n + 1) (41 + 42 n + 10 n ) N 2 annihilating operator , ---------- - --------------------- + N 2 2 (n + 4) (n + 4) Out of a total of , 7, cases 2, were successful and , 5, failed Success Rate: , 0.286 Here are the failures {{{[1, 3, 2, 4]}, {[4, 2, 3, 1]}}, {{[1, 3, 4, 2]}, {[1, 4, 2, 3]}, {[2, 3, 1, 4]}, {[2, 4, 3, 1]}, {[3, 1, 2, 4]}, {[3, 2, 4, 1]}, {[4, 1, 3, 2]}, {[4, 2, 1, 3]}}, {{[1, 4, 3, 2]}, {[2, 3, 4, 1]}, {[3, 2, 1, 4]}, {[4, 1, 2, 3]}}, {{[2, 1, 4, 3]}, {[3, 4, 1, 2]}}, {{[2, 4, 1, 3]}, {[3, 1, 4, 2]}}} {{{[1, 3, 2, 4]}, {[4, 2, 3, 1]}}, {{[1, 3, 4, 2]}, {[1, 4, 2, 3]}, {[2, 3, 1, 4]}, {[2, 4, 3, 1]}, {[3, 1, 2, 4]}, {[3, 2, 4, 1]}, {[4, 1, 3, 2]}, {[4, 2, 1, 3]}}, {{[1, 4, 3, 2]}, {[2, 3, 4, 1]}, {[3, 2, 1, 4]}, {[4, 1, 2, 3]}}, {{[2, 1, 4, 3]}, {[3, 4, 1, 2]}}, {{[2, 4, 1, 3]}, {[3, 1, 4, 2]}}} It took, 9387.794, seconds of CPU time .