Sz(2^21), r=7: r divides q-1, second rule, ppds of 2^84-1: [1429, 14449]
Zsigmondy pattern checked for 585 pairs (l, n); Lemma 3.4: 300 classes (l, f, r); Lemma 4.3: 39 classes (n, r); Lemma 3.3: 546 pairs (q, j)
3674 checks, 0 failed; time 22.4 s
ALL CHECKS PASSED
