With L1(k) = L(1) for D=-4*k:
a(1) = 1: L1(1) ~= 0.785398... = Pi/4;
L1(2) = 1.1107, L1(3) = 0.9069, L1(4) = 0.7854, L1(5) = 1.4050, L1(6) = 1.2825, all >= a(1);
a(2) = 7 because L1(7) = 0.5937 < a(1);
a(3) = 37 because L1(k) > a(2) for 8 <= k <= 36, L1(37) = 0.51647 < a(2).