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  2. Sum of two cubes - Wikipedia

    en.wikipedia.org/wiki/Sum_of_two_cubes

    A Taxicab number is the smallest positive number that can be expressed as a sum of two positive integer cubes in n distinct ways. The smallest taxicab number after Ta (1) = 1, is Ta (2) = 1729, [4] expressed as. or. Ta (3), the smallest taxicab number expressed in 3 different ways, is 87,539,319, expressed as. , or.

  3. List of sums of reciprocals - Wikipedia

    en.wikipedia.org/wiki/List_of_sums_of_reciprocals

    Then the triangle is in Euclidean space if the sum of the reciprocals of p, q, and r equals 1, spherical space if that sum is greater than 1, and hyperbolic space if the sum is less than 1. A harmonic divisor number is a positive integer whose divisors have a harmonic mean that is an integer. The first five of these are 1, 6, 28, 140, and 270.

  4. Sums of three cubes - Wikipedia

    en.wikipedia.org/wiki/Sums_of_three_cubes

    In the mathematics of sums of powers, it is an open problem to characterize the numbers that can be expressed as a sum of three cubes of integers, allowing both positive and negative cubes in the sum. A necessary condition for an integer to equal such a sum is that cannot equal 4 or 5 modulo 9, because the cubes modulo 9 are 0, 1, and −1, and ...

  5. Triangular number - Wikipedia

    en.wikipedia.org/wiki/Triangular_number

    A square whose side length is a triangular number can be partitioned into squares and half-squares whose areas add to cubes. This shows that the square of the n th triangular number is equal to the sum of the first n cube numbers. Also, the square of the n th triangular number is the same as the sum of the cubes of the integers 1 to n.

  6. Taxicab number - Wikipedia

    en.wikipedia.org/wiki/Taxicab_number

    In mathematics, the n th taxicab number, typically denoted Ta (n) or Taxicab (n), is defined as the smallest integer that can be expressed as a sum of two positive integer cubes in n distinct ways. [1] The most famous taxicab number is 1729 = Ta (2) = 1 3 + 12 3 = 9 3 + 10 3, also known as the Hardy-Ramanujan number. [2][3]

  7. Vieta's formulas - Wikipedia

    en.wikipedia.org/wiki/Vieta's_formulas

    Vieta's formulas can equivalently be written as for k = 1, 2, ..., n (the indices ik are sorted in increasing order to ensure each product of k roots is used exactly once). The left-hand sides of Vieta's formulas are the elementary symmetric polynomials of the roots. Vieta's system (*) can be solved by Newton's method through an explicit simple ...

  8. Divisor function - Wikipedia

    en.wikipedia.org/wiki/Divisor_function

    Sum of cubes of divisors, σ3 (n) up to n = 250. In mathematics, and specifically in number theory, a divisor function is an arithmetic function related to the divisors of an integer. When referred to as the divisor function, it counts the number of divisors of an integer (including 1 and the number itself). It appears in a number of remarkable ...

  9. Cube (algebra) - Wikipedia

    en.wikipedia.org/wiki/Cube_(algebra)

    Cube (algebra) y = x3 for values of 1 ≤ x ≤ 25. In arithmetic and algebra, the cube of a number n is its third power, that is, the result of multiplying three instances of n together. The cube of a number or any other mathematical expression is denoted by a superscript 3, for example 23 = 8 or (x + 1)3. The cube is also the number ...