From Wikipedia, the free encyclopedia
Natural number
251 (two hundred [and] fifty-one) is the natural number between
250 and
252. It is also a
prime number.
In mathematics
251 is:
- a
Sophie Germain prime.
[1]
- the sum of three consecutive primes (79 + 83 + 89) and seven consecutive primes (23 + 29 + 31 + 37 + 41 + 43 + 47).
- a
Chen prime.
- an
Eisenstein prime with no imaginary part.
- a
de Polignac number, meaning that it is odd and cannot be formed by adding a
power of two to a prime number.
[2]
[3]
- the smallest number that can be formed in more than one way by summing three positive cubes:
[4]
[5]
Every 5 × 5
matrix has exactly 251 square
submatrices.
[6]
References
-
^
Sloane, N. J. A. (ed.).
"Sequence A005384 (Sophie Germain primes p: 2p+1 is also prime)". The
On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
-
^
Sloane, N. J. A. (ed.).
"Sequence A006285 (Odd numbers not of form p + 2^x (de Polignac numbers))". The
On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
-
^ Kozek, Mark Robert (2007),
Applications of Covering Systems of Integers and Goldbach's Conjecture for Monic Polynomials, PhD dissertation, University of South Carolina, p. 14,
ISBN
9780549210207.
-
^
Sloane, N. J. A. (ed.).
"Sequence A008917 (Numbers that are the sum of 3 positive cubes in more than one way)". The
On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
-
^ De Koninck, Jean-Marie (2009),
Those fascinating numbers, Providence, RI: American Mathematical Society, p. 64,
ISBN
978-0-8218-4807-4,
MR
2532459.
-
^
Sloane, N. J. A. (ed.).
"Sequence A030662 (Number of combinations of n things from 1 to n at a time, with repeats allowed)". The
On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
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100,000
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1,000,000
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10,000,000
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100,000,000
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1,000,000,000
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