l = 0.6 (1 + 0.00 I); g = 9.8;
x0 = 0.01;
coord[n_] := Table[Subscript[x, i][t], {i, n}];
vel[n_] := D[coord[n], t];
mass[1] = {x0 Cos[[Omega] t], 0};
mass[i_] :=
  mass[i - 1] + {l Sin[Subscript[x, i - 1][t]], -l Cos[
      Subscript[x, i - 1][t]]};
ke[i_] := With[{v = D[mass[i + 1], t]}, v.v/2];
pe[i_] := g mass[i + 1][[2]];
L[n_] := Sum[ke[i] - pe[i], {i, n}];
eq[n_] :=
  Table[D[D[L[n], vel[n][[m]]], t] - D[L[n], coord[n][[m]]] == 0, {m,
    n}];
ic[n_] :=
  Table[{Subscript[x, i][0] == 0, Subscript[x, i]'[0] == 0}, {i, n}] //
    Flatten;

SOL[n_] :=
 NDSolve[{FullSimplify[eq[n]] /. [Omega] -> 1, ic[n]} // Flatten,
  Table[Subscript[x, i][t], {i, n}], {t, 0, 100},
  Method -> {"EquationSimplification" -> "Residual"}]

NDSolve::icfail: Unable to find initial conditions that satisfy the residual function within specified tolerances. Try giving initial conditions for both values and derivatives of the functions. >>