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  2. Smooth number - Wikipedia

    en.wikipedia.org/wiki/Smooth_number

    In number theory, an n-smooth (or n-friable) number is an integer whose prime factors are all less than or equal to n. [1] [2] For example, a 7-smooth number is a number in which every prime factor is at most 7. Therefore, 49 = 7 2 and 15750 = 2 × 3 2 × 5 3 × 7 are both 7-smooth, while 11 and 702 = 2 × 3 3 × 13 are not 7-smooth.

  3. Abundant number - Wikipedia

    en.wikipedia.org/wiki/Abundant_number

    The smallest odd integer with abundancy index exceeding 3 is 1018976683725 = 3 3 × 5 2 × 7 2 × 11 × 13 × 17 × 19 × 23 × 29. [8] If p = (p 1, ..., p n) is a list of primes, then p is termed abundant if some integer composed only of primes in p is abundant. A necessary and sufficient condition for this is that the product of p i /(p i − ...

  4. Integer factorization - Wikipedia

    en.wikipedia.org/wiki/Integer_factorization

    Let Δ be a negative integer with Δ = −dn, where d is a multiplier and Δ is the negative discriminant of some quadratic form. Take the t first primes p 1 = 2, p 2 = 3, p 3 = 5, ..., p t, for some t ∈ N. Let f q be a random prime form of G Δ with (⁠ Δ / q ⁠) = 1. Find a generating set X of G Δ.

  5. Table of prime factors - Wikipedia

    en.wikipedia.org/wiki/Table_of_prime_factors

    An odd number does not have the prime factor 2. The first: 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23 (sequence A005408 in the OEIS). All integers are either even or odd. A square has even multiplicity for all prime factors (it is of the form a 2 for some a). The first: 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144 (sequence A000290 in the OEIS).

  6. Trial division - Wikipedia

    en.wikipedia.org/wiki/Trial_division

    It can be shown that 88% of all positive integers have a factor under 100 and that 92% have a factor under 1000. Thus, when confronted by an arbitrary large a , it is worthwhile to check for divisibility by the small primes, since for a = 1000 {\displaystyle a=1000} , in base-2 n = 10 {\displaystyle n=10} .

  7. Senary - Wikipedia

    en.wikipedia.org/wiki/Senary

    Thus, the base-36 number WIKI 36 is equal to the senary number 52303230 6. In decimal, it is 1,517,058. In decimal, it is 1,517,058. The choice of 36 as a radix is convenient in that the digits can be represented using the Arabic numerals 0–9 and the Latin letters A–Z; this choice is the basis of the base36 encoding scheme.

  8. Fermat's factorization method - Wikipedia

    en.wikipedia.org/wiki/Fermat's_factorization_method

    The values repeat with each increase of a by 10. In this example, N is 17 mod 20, so subtracting 17 mod 20 (or adding 3), produces 3, 4, 7, 8, 12, and 19 modulo 20 for these values. It is apparent that only the 4 from this list can be a square.

  9. Pollard's rho algorithm - Wikipedia

    en.wikipedia.org/wiki/Pollard's_rho_algorithm

    The ρ algorithm was a good choice for F 8 because the prime factor p = 1238926361552897 is much smaller than the other factor. The factorization took 2 hours on a UNIVAC 1100/42 . [ 4 ]