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  2. Sum of two cubes - Wikipedia

    en.wikipedia.org/wiki/Sum_of_two_cubes

    A Cabtaxi number is the smallest positive number that can be expressed as a sum of two integer cubes in n ways, allowing the cubes to be negative or zero as well as positive. The smallest cabtaxi number after Cabtaxi (1) = 0, is Cabtaxi (2) = 91, [5] expressed as: Cabtaxi (3), the smallest Cabtaxi number expressed in 3 different ways, is 4104 ...

  3. 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 ...

  4. Waring's problem - Wikipedia

    en.wikipedia.org/wiki/Waring's_problem

    Waring's problem. In number theory, Waring's problem asks whether each natural number k has an associated positive integer s such that every natural number is the sum of at most s natural numbers raised to the power k. For example, every natural number is the sum of at most 4 squares, 9 cubes, or 19 fourth powers.

  5. Sum of four cubes problem - Wikipedia

    en.wikipedia.org/wiki/Sum_of_four_cubes_problem

    The sum of four cubes problem[1] asks whether every integer is the sum of four cubes of integers. It is conjectured the answer is affirmative, but this conjecture has been neither proven nor disproven. [2] Some of the cubes may be negative numbers, in contrast to Waring's problem on sums of cubes, where they are required to be positive.

  6. 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 ...

  7. 1729 (number) - Wikipedia

    en.wikipedia.org/wiki/1729_(number)

    1729 (number) 1729 is the natural number following 1728 and preceding 1730. It is the first nontrivial taxicab number, expressed as the sum of two cubic numbers in two different ways. It is also known as the Ramanujan number or Hardy–Ramanujan number, named after G. H. Hardy and Srinivasa Ramanujan.

  8. Squared triangular number - Wikipedia

    en.wikipedia.org/wiki/Squared_triangular_number

    The sum within each gmonon is a cube, so the sum of the whole table is a sum of cubes. Visual demonstration that the square of a triangular number equals a sum of cubes. In the more recent mathematical literature, Edmonds (1957) provides a proof using summation by parts.

  9. 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 ...