Williams's p + 1 algorithm
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In computational number theory, Williams p + 1 algorithm is an integer factorization algorithm invented by H. C. Williams.
It 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. It uses Lucas sequences.
It is analogous to Pollard's p-1 algorithm.
Reference
H.C. Williams, A p+1 method of factoring, Math. Comp., 39, 225-234 (1982)