Problem mit for bzw. foreach -Schleife bei Knotenpunkte (nodes)

\documentclass[margin=5pt,tikz]{standalone}
\usetikzlibrary{calc,intersections}
\begin{document}
\begin{tikzpicture}[every node/.append style={minimum width=1cm, minimum height=1cm}]
  % Eckpunkte
  \node (1) at (16,16)  {1};
  \node (2) at (1,16)   {2};
  \node (3) at (2,0)    {3};
  \node (4) at (9,0)    {4};

  % Gitterpunkte der oberen und unteren Seite:

  \def \s{7} % Zwischenspaltenanzahl (Senkrechten)

  \foreach \n in {1, ..., \s}
  {
    \node (O\n) at ($ (1) !.{(1 / (\s + 1)) * \n}! (2) $) {O\n}; 
    \node (U\n) at ($ (4) !.{(1 / (\s + 1)) * \n}! (3) $) {U\n};
  }

  % Gitterpunkte der linken und rechten Seite:

  \def \w{6} % Zwischenzeilenanzahl (Waagerechten)

  \foreach \n in {1, ..., \w}
  {
    \node (L\n) at ($ (2) !.{(1 / (\w + 1)) * \n}! (3) $) {L\n}; 
    \node (R\n) at ($ (1) !.{(1 / (\w + 1)) * \n}! (4) $) {R\n};
  }

  % Festlegung senkrechter und waagerechter Reihen:

  \foreach \n in {1, ..., \s}
    \path [name path global/.expanded=O\n--U\n] (O\n) -- (U\n);

  \foreach \n in {1, ..., \w}
    \path [name path global/.expanded=L\n--R\n] (L\n) -- (R\n);

  % Schnittpunkte der senkrechen mit den waagerechten Reihen als neue Gitterpunkte:

 % \def \i{1}

 % \foreach \n in {1, ..., \s}
 % {
 %   \path [name intersections = {of=O\n--U\n and L\i--R\i, by=\n\i}]; \node at (\n\i) {\n\i};
 % }

  \path [name intersections = {of=O1--U1 and L1--R1, by=11}]; \node at (11) {11};
  \path [name intersections = {of=O2--U2 and L1--R1, by=21}]; \node at (21) {21};
  \path [name intersections = {of=O3--U3 and L1--R1, by=31}]; \node at (31) {31};
  \path [name intersections = {of=O4--U4 and L1--R1, by=41}]; \node at (41) {41};
  \path [name intersections = {of=O5--U5 and L1--R1, by=51}]; \node at (51) {51};
  \path [name intersections = {of=O6--U6 and L1--R1, by=61}]; \node at (61) {61};
  \path [name intersections = {of=O7--U7 and L1--R1, by=71}]; \node at (71) {71};

  \path [name intersections = {of=O1--U1 and L2--R2, by=12}]; \node at (12) {12};
  \path [name intersections = {of=O2--U2 and L2--R2, by=22}]; \node at (22) {22};
  \path [name intersections = {of=O3--U3 and L2--R2, by=32}]; \node at (32) {32};
  \path [name intersections = {of=O4--U4 and L2--R2, by=42}]; \node at (42) {42};
  \path [name intersections = {of=O5--U5 and L2--R2, by=52}]; \node at (52) {52};
  \path [name intersections = {of=O6--U6 and L2--R2, by=62}]; \node at (62) {62};
  \path [name intersections = {of=O7--U7 and L2--R2, by=72}]; \node at (72) {72};

  \path [name intersections = {of=O1--U1 and L3--R3, by=13}]; \node at (13) {13};
  \path [name intersections = {of=O2--U2 and L3--R3, by=23}]; \node at (23) {23};
  \path [name intersections = {of=O3--U3 and L3--R3, by=33}]; \node at (33) {33};
  \path [name intersections = {of=O4--U4 and L3--R3, by=43}]; \node at (43) {43};
  \path [name intersections = {of=O5--U5 and L3--R3, by=53}]; \node at (53) {53};
  \path [name intersections = {of=O6--U6 and L3--R3, by=63}]; \node at (63) {63};
  \path [name intersections = {of=O7--U7 and L3--R3, by=73}]; \node at (73) {73};

  \path [name intersections = {of=O1--U1 and L4--R4, by=14}]; \node at (14) {14};
  \path [name intersections = {of=O2--U2 and L4--R4, by=24}]; \node at (24) {24};
  \path [name intersections = {of=O3--U3 and L4--R4, by=34}]; \node at (34) {34};
  \path [name intersections = {of=O4--U4 and L4--R4, by=44}]; \node at (44) {44};
  \path [name intersections = {of=O5--U5 and L4--R4, by=54}]; \node at (54) {54};
  \path [name intersections = {of=O6--U6 and L4--R4, by=64}]; \node at (64) {64};
  \path [name intersections = {of=O7--U7 and L4--R4, by=74}]; \node at (74) {74};

  \path [name intersections = {of=O1--U1 and L5--R5, by=15}]; \node at (15) {15};
  \path [name intersections = {of=O2--U2 and L5--R5, by=25}]; \node at (25) {25};
  \path [name intersections = {of=O3--U3 and L5--R5, by=35}]; \node at (35) {35};
  \path [name intersections = {of=O4--U4 and L5--R5, by=45}]; \node at (45) {45};
  \path [name intersections = {of=O5--U5 and L5--R5, by=55}]; \node at (55) {55};
  \path [name intersections = {of=O6--U6 and L5--R5, by=65}]; \node at (65) {65};
  \path [name intersections = {of=O7--U7 and L5--R5, by=75}]; \node at (75) {75};

  \path [name intersections = {of=O1--U1 and L6--R6, by=16}]; \node at (16) {16};
  \path [name intersections = {of=O2--U2 and L6--R6, by=26}]; \node at (26) {26};
  \path [name intersections = {of=O3--U3 and L6--R6, by=36}]; \node at (36) {36};
  \path [name intersections = {of=O4--U4 and L6--R6, by=46}]; \node at (46) {46};
  \path [name intersections = {of=O5--U5 and L6--R6, by=56}]; \node at (56) {56};
  \path [name intersections = {of=O6--U6 and L6--R6, by=66}]; \node at (66) {66};
  \path [name intersections = {of=O7--U7 and L6--R6, by=76}]; \node at (76) {76};

\end{tikzpicture}
\end{document}