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This is a list of articles about prime numbers. A prime number (or prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself. By Euclid's theorem, there are an infinite number of prime numbers. Subsets of the prime numbers may be generated with various formulas for primes.
A sphenic number has Ω(n) = 3 and is square-free (so it is the product of 3 distinct primes). The first: 30, 42, 66, 70, 78, 102, 105, 110, 114, 130, 138, 154 (sequence A007304 in the OEIS). a 0 (n) is the sum of primes dividing n, counted with multiplicity. It is an additive function.
Klauber's 1932 paper describes a triangle in which row n contains the numbers (n − 1) 2 + 1 through n 2. As in the Ulam spiral, quadratic polynomials generate numbers that lie in straight lines. Vertical lines correspond to numbers of the form k 2 − k + M. Vertical and diagonal lines with a high density of prime numbers are evident in the ...
where p k is the k th prime number. For instance, p 5 # signifies the product of the first 5 primes: # = = The first five primorials p n # are: 2, 6, 30, 210, 2310 (sequence A002110 in the OEIS). The sequence also includes p 0 # = 1 as empty product.
A list of articles about numbers (not about numerals). Topics include powers of ten, notable integers, prime and cardinal numbers, and the myriad system.
They can’t make “twenty” into “twenty-nine” if it already says “Three hundred twenty and 00/100.” Hyphenate all numbers under 100 that need more than one word. For example, $73 is ...
The number of grains of wheat on the second half of the chessboard is 2 32 + 2 33 + 2 34 + ... + 2 63, for a total of 2 64 − 2 32 grains. This is equal to the square of the number of grains on the first half of the board, plus itself. The first square of the second half alone contains one more grain than the entire first half.
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