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The primes of the form 2n+1 are the odd primes, including all primes other than 2. Some sequences have alternate names: 4n+1 are Pythagorean primes, 4n+3 are the integer Gaussian primes, and 6n+5 are the Eisenstein primes (with 2 omitted).
4-4-6-2. AT&SF locomotive no. 1300, a 4-4-6-2 Mallet type. Under the Whyte notation for the classification of steam locomotive wheel arrangements, a 4-4-6-2 is a locomotive with two pairs of leading wheels, one set of four driving wheels, a second set of six driving wheels, and a pair of trailing wheels . The equivalent UIC classification is ...
Four fours. Four fours is a mathematical puzzle, the goal of which is to find the simplest mathematical expression for every whole number from 0 to some maximum, using only common mathematical symbols and the digit four. No other digit is allowed. Most versions of the puzzle require that each expression have exactly four fours, but some ...
CV-4 Ranger: Ranger (lead ship) 4 June 1934 18 October 1946 12 years, 136 days Scrapped in 1947 [18] CV-5 Yorktown: Yorktown (lead ship) 30 September 1937 7 June 1942 4 years, 250 days Sunk in the Battle of Midway in 1942 [19] CV-6 Enterprise: Yorktown: 12 May 1938 17 February 1947 8 years, 281 days Scrapped in 1960 [20] CV-7 Wasp: Wasp (lead ...
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South Africa. CGR Type A 2-6-4T. Between 1898 and 1900, the Pretoria-Pietersburg Railway (PPR) placed six 2-6-4T locomotives in service, built by Beyer, Peacock & Company. During the Second Boer War, they were first taken over by the Nederlandsche-Zuid-Afrikaansche Spoorwegmaatschappij (NZASM) and then by the Imperial Military Railways (IMR).
The introduction of the 4-6-2 design in 1901 has been described as "a veritable milestone in locomotive progress". [3] On many railways worldwide, Pacific steam locomotives provided the motive power for express passenger trains throughout much of the early to mid-20th century, before either being superseded by larger types in the late 1940s and 1950s, or replaced by electric or diesel-electric ...
List of chemical elements. 118 chemical elements have been identified and named officially by IUPAC. A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z ). [ 1]