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  2. Bell number - Wikipedia

    en.wikipedia.org/wiki/Bell_number

    The triangular array whose right-hand diagonal sequence consists of Bell numbers. The Bell numbers can easily be calculated by creating the so-called Bell triangle, also called Aitken's array or the Peirce triangle after Alexander Aitken and Charles Sanders Peirce. [ 6 ] Start with the number one.

  3. Pisano period - Wikipedia

    en.wikipedia.org/wiki/Pisano_period

    The Pisano period, denoted π (n), is the length of the period of this sequence. For example, the sequence of Fibonacci numbers modulo 3 begins: This sequence has period 8, so π (3) = 8. For n = 3, this is a visualization of the Pisano period in the two-dimensional state space of the recurrence relation.

  4. Telephone keypad - Wikipedia

    en.wikipedia.org/wiki/Telephone_keypad

    A telephone keypad using the ITU E.161 standard. A telephone keypad is a keypad installed on a push-button telephone or similar telecommunication device for dialing a telephone number. It was standardized when the dual-tone multi-frequency signaling (DTMF) system was developed in the Bell System in the United States in the 1960s – this ...

  5. Modular arithmetic - Wikipedia

    en.wikipedia.org/wiki/Modular_arithmetic

    Time-keeping on this clock uses arithmetic modulo 12. Adding 4 hours to 9 o'clock gives 1 o'clock, since 13 is congruent to 1 modulo 12. In mathematics, modular arithmetic is a system of arithmetic for integers, where numbers "wrap around" when reaching a certain value, called the modulus. The modern approach to modular arithmetic was developed ...

  6. Bell polynomials - Wikipedia

    en.wikipedia.org/wiki/Bell_polynomials

    Bell polynomials. In combinatorial mathematics, the Bell polynomials, named in honor of Eric Temple Bell, are used in the study of set partitions. They are related to Stirling and Bell numbers. They also occur in many applications, such as in Faà di Bruno's formula.

  7. Password strength - Wikipedia

    en.wikipedia.org/wiki/Password_strength

    Password strength is specified by the amount of information entropy, which is measured in shannon (Sh) and is a concept from information theory. It can be regarded as the minimum number of bits necessary to hold the information in a password of a given type.

  8. Bell triangle - Wikipedia

    en.wikipedia.org/wiki/Bell_triangle

    Bell triangle. In mathematics, the Bell triangle is a triangle of numbers analogous to Pascal's triangle, whose values count partitions of a set in which a given element is the largest singleton. It is named for its close connection to the Bell numbers, [1] which may be found on both sides of the triangle, and which are in turn named after Eric ...

  9. Multiplicative order - Wikipedia

    en.wikipedia.org/wiki/Multiplicative_order

    The multiplicative order of a number a modulo n is the order of a in the multiplicative group whose elements are the residues modulo n of the numbers coprime to n, and whose group operation is multiplication modulo n. This is the group of units of the ring Zn; it has φ (n) elements, φ being Euler's totient function, and is denoted as U (n) or ...