Akm[k_,m_]:=Piecewise[{{0, (k != 1 && k != 3 && k != 5) || (k != 3 && k != 5 && m != -1 && m != 0 && m != 1) || (k != 5 && m != -3 && m != -2 && m != -1 && m != 0 && m != 1 && m != 2 && m != 3) || (m != -5 && m != -4 && m != -3 && m != -2 && m != -1 && m != 0 && m != 1 && m != 2 && m != 3 && m != 4 && m != 5)}, {I*B[1, 1], k == 1 && (m == -1 || m == 1)}, {A[1, 0], k == 1 && m == 0}, {I*B[3, 3], k == 3 && (m == -3 || m == 3)}, {A[3, 2], k == 3 && (m == -2 || m == 2)}, {I*B[3, 1], k == 3 && (m == -1 || m == 1)}, {A[3, 0], k == 3 && m == 0}, {I*B[5, 5], k == 5 && (m == -5 || m == 5)}, {A[5, 4], k == 5 && (m == -4 || m == 4)}, {I*B[5, 3], k == 5 && (m == -3 || m == 3)}, {A[5, 2], k == 5 && (m == -2 || m == 2)}, {I*B[5, 1], k == 5 && (m == -1 || m == 1)}}, A[5, 0]]