Census of stopping times sigma(n), T(x) = x/2 or (3x+1)/2, every n in [2^(L-1), 2^L), L = 3..34.
out_L<L>.txt : "H L s count" = exact histogram of sigma on the L-bit shell; "R L n sigma a maxheight" = 8 largest sigma.
sigma_hist.c : the program that produced out_L*.txt (unsigned __int128 arithmetic, step cap 4096; max sigma found = 547).
sigma_hist_max.c : same program plus the running maximum of the orbit value before stopping (printed to stderr).
xmax_all.txt : for each L, log2 of that maximum, and whether its histogram is identical to out_L<L>.txt.
  Result: the maximum over all n < 2^34 is 2^63.17 (L = 34), far below 2^127, so the 128-bit arithmetic cannot
  overflow; all 32 histograms are reproduced bit for bit. (Cross-check: the L = 33 maximum 2^62.98 is half the 3x+1 peak
  18,144,594,937,356,598,024 of n = 8,528,817,511, a path record, recomputed directly.)
Build/run: gcc -O2 -o sigma_hist_max sigma_hist_max.c -lm ; ./sigma_hist_max L > out.txt   (L = 34: about 2 min)
analyze.py -> analysis_out.txt : ratios actual/model at N = L..6L and max sigma vs the model count-1 point.
delay_check.py -> delay_check_out.txt : endpoint-height law under the excursion measure; ratios at N = L + d, d <= 12.
excursion_dp.py : O(N^2) exact excursion Fourier sums S_N(h). lw_pair_check.py -> lw_pair_check_out.txt : the audit
  of the pair majorant (post 61, 09:31Z).
