Category: Integers A Leyland number is an integer of the form xy + yx with 1 < x ≤ y. ... In recreational mathematics, a repunit is a number like 11, 111, or 1111 that contains only the digit 1. ... In mathematics, a Keith number or repfigit number is an integer that appears as a term in a linear recurrence relation with initial terms based off its own digits. ... A Markov number or Markoff number is an integer x, y or z that is part of a solution to the Markov Diophantine equation The first few Markov numbers are 1, 2, 5, 13, 29, 34, 89, 169, 194, 233, 433, 610, 985, 1325, ... (sequence A002559 in OEIS) appearing in... A cup of coffee Workers sorting and pulping coffee beans in Guatemala Mature coffee fruit still on the plant Coffee is a widely consumed beverage prepared from the roasted seeds — commonly referred to as beans — of the coffee plant. ... A domino tiling of a region in the Euclidean plane is a tessellation of the region by dominos, shapes formed by the union of two unit squares meeting edge-to-edge. ... A tiling with squares whose sides are successive Fibonacci numbers in length A Fibonacci spiral, created by drawing arcs connecting the opposite corners of squares in the Fibonacci tiling shown above - see golden spiral. ... In mathematics, the Pell numbers and companion Pell numbers (Pell-Lucas numbers) are both sequences of integers. ... A Carol number, named after Carol G. Kirnon, is an integer of the form . ... In mathematics and computer science, hexadecimal, base-16, or simply hex, is a numeral system with a radix, or base, of 16, usually written using the symbols 0–9 and A–F, or a–f. ... Truecolor (also spelled Truecolour; called Millions on a Macintosh) graphics is a method of storing image information in a computers memory such that each pixel is represented by three or more bytes. ... A Kynéa number (pronounced: Ka-Nay), named after Kynéa R. Griffith, is an integer of the form . ... In mathematics, a Motzkin number for a given number n is the number of different ways of drawing non-intersecting chords on a circle between n points. ... A Wedderburn-Etherington number counts how many weakly binary trees can be constructed such that each graph vertex (not counting the root vertex) is adjacent to no more than three other such vertices, for a given number of nodes. ... In mathematics, a colossally abundant number (sometimes abbreviated as CA) is a certain kind of natural number. ... In recreational mathematics, a repdigit is a natural number composed of repeated instances of the same digit, most often in the decimal numeral system. ... The Bell numbers, named in honor of Eric Temple Bell, are a sequence of integers arising in combinatorics that begins thus (sequence A000110 in OEIS): In general, Bn is the number of partitions of a set of size n. ... In mathematics, a perfect number is defined as an integer which is the sum of its proper positive divisors, that is, the sum of the positive divisors not including the number. ... An alternating factorial is the sum of the first n factorials with the odd-indexed factorials multiplied by −1 if n is even, and the even-indexed factorials multiplied by −1 if n is odd, resulting in an alternation of signs of the summands (or alternation of addition and subtraction... For factorial rings in mathematics, see unique factorisation domain. ... A factorial prime is a number that is one less or one more than a factorial and is also a prime number. ... The vigesimal or base-20 numeral system is based on twenty (in the same way in which the ordinary decimal numeral system is based on ten). ... Page 9 of the Dresden Codex showing the classic Maya language written in Mayan hieroglyphs (from the 1880 Förstermann edition) The Mayan languages (alternatively: Maya languages)[1] form a language family spoken in Mesoamerica and northern Central America. ... Nahuatl is a native language of central Mexico. ... In mathematics, the n-th taxicab number, typically denoted Ta(n) or Taxicab(n), is defined as the smallest number which can be expressed as a sum of two positive cubes in n distinct ways, up to order of summands. ... A Friedman number is an integer which, in a given base, is the result of an expression using all its own digits in combination with any of the four basic arithmetic operators (+, -, ×, ÷) and sometimes exponentiation. ...