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  2. Ulam number - Wikipedia

    en.wikipedia.org/wiki/Ulam_number

    Apart from 1 + 2 = 3 any subsequent Ulam number cannot be the sum of its two prior consecutive Ulam numbers. Proof: Assume that for n > 2, U n−1 + U n = U n+1 is the required sum in only one way; then so does U n−2 + U n produce a sum in only one way, and it falls between U n and U n+1.

  3. Fibonacci sequence - Wikipedia

    en.wikipedia.org/wiki/Fibonacci_sequence

    Moreover, every positive integer can be written in a unique way as the sum of one or more distinct Fibonacci numbers in such a way that the sum does not include any two consecutive Fibonacci numbers. This is known as Zeckendorf's theorem , and a sum of Fibonacci numbers that satisfies these conditions is called a Zeckendorf representation.

  4. Goldbach's conjecture - Wikipedia

    en.wikipedia.org/wiki/Goldbach's_conjecture

    In particular, the set of even integers that are not the sum of two primes has density zero. In 1951, Yuri Linnik proved the existence of a constant K such that every sufficiently large even number is the sum of two primes and at most K powers of 2. János Pintz and Imre Ruzsa found in 2020 that K = 8 works. [19]

  5. Prefix sum - Wikipedia

    en.wikipedia.org/wiki/Prefix_sum

    Express each term of the final sequence y 0, y 1, y 2, ... as the sum of up to two terms of these intermediate sequences: y 0 = x 0, y 1 = z 0, y 2 = z 0 + x 2, y 3 = w 1, etc. After the first value, each successive number y i is either copied from a position half as far through the w sequence, or is the previous value added to one value in the ...

  6. Composition (combinatorics) - Wikipedia

    en.wikipedia.org/wiki/Composition_(combinatorics)

    For example the five compositions of 5 into distinct terms are: 5; 4 + 1; 3 + 2; 2 + 3; 1 + 4. Compare this with the three partitions of 5 into distinct terms: 5; 4 + 1; 3 + 2. Note that the ancient Sanskrit sages discovered many years before Fibonacci that the number of compositions of any natural number n as the sum of 1's and 2's is the nth ...

  7. Summation - Wikipedia

    en.wikipedia.org/wiki/Summation

    In mathematics, summation is the addition of a sequence of numbers, called addends or summands; the result is their sum or total.Beside numbers, other types of values can be summed as well: functions, vectors, matrices, polynomials and, in general, elements of any type of mathematical objects on which an operation denoted "+" is defined.

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    mail.aol.com

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  9. Aliquot sequence - Wikipedia

    en.wikipedia.org/wiki/Aliquot_sequence

    The aliquot sequence starting with a positive integer k can be defined formally in terms of the sum-of-divisors function σ 1 or the aliquot sum function s in the following way: [1] = = = > = = = If the s n-1 = 0 condition is added, then the terms after 0 are all 0, and all aliquot sequences would be infinite, and we can conjecture that all aliquot sequences are convergent, the limit of these ...