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  2. Hückel's rule - Wikipedia

    en.wikipedia.org/wiki/Hückel's_rule

    In 2011, Jordi Poater and Miquel Solà expanded the rule to open-shell spherical compounds, finding they were aromatic when they had 2n 2 + 2n + 1 π-electrons, with spin S = (n + 1/2) - corresponding to a half-filled last energy level with the same spin. For instance C 60 1– is also observed to be aromatic with a spin of 11/2. [16]

  3. Madhava's correction term - Wikipedia

    en.wikipedia.org/wiki/Madhava's_correction_term

    Madhava's correction term is a mathematical expression attributed to Madhava of Sangamagrama (c. 1340 – c. 1425), the founder of the Kerala school of astronomy and mathematics, that can be used to give a better approximation to the value of the mathematical constant π (pi) than the partial sum approximation obtained by truncating the Madhava–Leibniz infinite series for π.

  4. List of formulae involving π - Wikipedia

    en.wikipedia.org/wiki/List_of_formulae_involving_π

    is the number of collisions made (in ideal conditions, perfectly elastic with no friction) by an object of mass m initially at rest between a fixed wall and another object of mass b 2N m, when struck by the other object. [1] (This gives the digits of π in base b up to N digits past the radix point.)

  5. Central binomial coefficient - Wikipedia

    en.wikipedia.org/wiki/Central_binomial_coefficient

    The central binomial coefficients give the number of possible number of assignments of n-a-side sports teams from 2n players, taking into account the playing area side The central binomial coefficient ( 2 n n ) {\displaystyle {\binom {2n}{n}}} is the number of arrangements where there are an equal number of two types of objects.

  6. Fermat's theorem on sums of two squares - Wikipedia

    en.wikipedia.org/wiki/Fermat's_theorem_on_sums_of...

    2. Second proof. This proof builds on Lagrange's result that if p = 4 n + 1 {\displaystyle p=4n+1} is a prime number, then there must be an integer m such that m 2 + 1 {\displaystyle m^{2}+1} is divisible by p (we can also see this by Euler's criterion ); it also uses the fact that the Gaussian integers are a unique factorization domain ...

  7. List of mathematical series - Wikipedia

    en.wikipedia.org/wiki/List_of_mathematical_series

    2.3 Trigonometric, inverse trigonometric, hyperbolic, and inverse hyperbolic functions relationship. 2.4 Modified-factorial denominators. 2.5 Binomial coefficients.

  8. Fermat number - Wikipedia

    en.wikipedia.org/wiki/Fermat_number

    Euler proved that every factor of F n must have the form k 2 n+1 + 1 (later improved to k 2 n+2 + 1 by Lucas) for n ≥ 2. That 641 is a factor of F 5 can be deduced from the equalities 641 = 2 7 × 5 + 1 and 641 = 2 4 + 5 4 .

  9. Polygonal number - Wikipedia

    en.wikipedia.org/wiki/Polygonal_number

    ⁠ 1 / 2 ⁠ (4n 22n) = 2n 2 - n: 1 6 15 28 45 66 91 120 153 190 2 ln 2 [3] A000384: 7: Heptagonal