Williams's p + 1 algorithm

An Integer factorization algorithm invented by H.C. Williams that works well if the number N to be factored contains one or more prime factors p such that p+1 is smooth, i.e. p+1 contains only small factors. Uses Lucas sequences.

Analogous to Pollard's p-1 algorithm.

See H.C. Williams, A p+1 method of factoring, Math. Comp., 39, 225-234 (1982)