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  2. Triangular number - Wikipedia

    en.wikipedia.org/wiki/Triangular_number

    No odd perfect numbers are known; hence, all known perfect numbers are triangular. For example, the third triangular number is (3 × 2 =) 6, the seventh is (7 × 4 =) 28, the 31st is (31 × 16 =) 496, and the 127th is (127 × 64 =) 8128. The final digit of a triangular number is 0, 1, 3, 5, 6, or 8, and thus such numbers never end in 2, 4, 7, or 9.

  3. Category:Triangles of numbers - Wikipedia

    en.wikipedia.org/wiki/Category:Triangles_of_numbers

    Pages in category "Triangles of numbers" The following 29 pages are in this category, out of 29 total. ... Triangle of partition numbers; Trinomial triangle; W.

  4. De numeris triangularibus et inde de progressionibus ...

    en.wikipedia.org/wiki/De_numeris_triangularibus...

    Repeating this process produces the higher-order binomial coefficients, which in this way can be thought of as generalized triangular numbers, and which give the first part of Harriot's title. [3] Harriot's results were only improved 50 years later by Isaac Newton, and prefigure Newton's use of Newton polynomials for interpolation.

  5. Centered triangular number - Wikipedia

    en.wikipedia.org/wiki/Centered_triangular_number

    Each centered triangular number has a remainder of 1 when divided by 3, and the quotient (if positive) is the previous regular triangular number. Each centered triangular number from 10 onwards is the sum of three consecutive regular triangular numbers. For n > 2, the sum of the first n centered triangular numbers is the magic constant for an n ...

  6. Tetrahedral number - Wikipedia

    en.wikipedia.org/wiki/Tetrahedral_number

    Te n is the sum of all products p × q where (p, q) are ordered pairs and p + q = n + 1; Te n is the number of (n + 2)-bit numbers that contain two runs of 1's in their binary expansion. The largest tetrahedral number of the form + + for some integers and is 8436.

  7. List of types of numbers - Wikipedia

    en.wikipedia.org/wiki/List_of_types_of_numbers

    Such a number is algebraic and can be expressed as the sum of a rational number and the square root of a rational number. Constructible number: A number representing a length that can be constructed using a compass and straightedge. Constructible numbers form a subfield of the field of algebraic numbers, and include the quadratic surds.

  8. Doubly triangular number - Wikipedia

    en.wikipedia.org/wiki/Doubly_triangular_number

    In mathematics, the doubly triangular numbers are the numbers that appear within the sequence of triangular numbers, in positions that are also triangular numbers. That is, if T n = n ( n + 1 ) / 2 {\displaystyle T_{n}=n(n+1)/2} denotes the n {\displaystyle n} th triangular number, then the doubly triangular numbers are the numbers of the form ...

  9. Square triangular number - Wikipedia

    en.wikipedia.org/wiki/Square_triangular_number

    All square triangular numbers have the form , where is a convergent to the continued fraction expansion of , the square root of 2. [ 4 ] A. V. Sylwester gave a short proof that there are infinitely many square triangular numbers: If the n {\displaystyle n} th triangular number n ( n + 1 ) 2 {\displaystyle {\tfrac {n(n+1)}{2}}} is square, then ...