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  2. Formulas for generating Pythagorean triples - Wikipedia

    en.wikipedia.org/wiki/Formulas_for_generating...

    Leonardo of Pisa (c. 1170 – c. 1250) described this method [1] [2] for generating primitive triples using the sequence of consecutive odd integers ,,,,, … and the fact that the sum of the first n terms of this sequence is .

  3. List of sums of reciprocals - Wikipedia

    en.wikipedia.org/wiki/List_of_sums_of_reciprocals

    The harmonic mean of a set of positive integers is the number of numbers times the reciprocal of the sum of their reciprocals. The optic equation requires the sum of the reciprocals of two positive integers a and b to equal the reciprocal of a third positive integer c. All solutions are given by a = mn + m 2, b = mn + n 2, c = mn.

  4. Parity (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Parity_(mathematics)

    Even and odd numbers have opposite parities, e.g., 22 (even number) and 13 (odd number) have opposite parities. In particular, the parity of zero is even. [2] Any two consecutive integers have opposite parity. A number (i.e., integer) expressed in the decimal numeral system is even or odd according to whether its last digit is even or odd. That ...

  5. Polite number - Wikipedia

    en.wikipedia.org/wiki/Polite_number

    In number theory, a polite number is a positive integer that can be written as the sum of two or more consecutive positive integers. A positive integer which is not polite is called impolite . [ 1 ] [ 2 ] The impolite numbers are exactly the powers of two , and the polite numbers are the natural numbers that are not powers of two.

  6. Integer partition - Wikipedia

    en.wikipedia.org/wiki/Integer_partition

    Polite number, defined by partitions into consecutive integers; Multiplicative partition; Twelvefold way; Ewens's sampling formula; Faà di Bruno's formula; Multipartition; Newton's identities; Smallest-parts function; A Goldbach partition is the partition of an even number into primes (see Goldbach's conjecture) Kostant's partition function

  7. Pythagorean triple - Wikipedia

    en.wikipedia.org/wiki/Pythagorean_triple

    Gaussian integers are complex numbers of the form α = u + vi, where u and v are ordinary integers and i is the square root of negative one. The units of Gaussian integers are ±1 and ±i. The ordinary integers are called the rational integers and denoted as ' Z '. The Gaussian integers are denoted as Z[i].

  8. Collatz conjecture - Wikipedia

    en.wikipedia.org/wiki/Collatz_conjecture

    Then the formula for the map is exactly the same as when the domain is the integers: an 'even' such rational is divided by 2; an 'odd' such rational is multiplied by 3 and then 1 is added. A closely related fact is that the Collatz map extends to the ring of 2-adic integers , which contains the ring of rationals with odd denominators as a subring.

  9. List of integer sequences - Wikipedia

    en.wikipedia.org/wiki/List_of_integer_sequences

    The length of an interval of consecutive integers with property that every element has a factor in common with one of the endpoints. A059756: Sierpinski numbers: 78557, 271129, 271577, 322523, 327739, 482719, 575041, 603713, 903983, 934909, ... Odd k for which { k⋅2 n + 1 : n ∈ } consists only of composite numbers. A076336