Английская Википедия:79 (number)
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Шаблон:Infobox number 79 (seventy-nine) is the natural number following 78 and preceding 80.
In mathematics
79 is:
- An odd number.
- The smallest number that can not be represented as a sum of fewer than 19 fourth powers.
- The 22nd prime number (between Шаблон:Num and Шаблон:Num)
- An isolated prime without a twin prime, as 77 and 81 are composite.[1]
- The smallest prime number p for which the real quadratic field Q[[[:Шаблон:Sqrt]]] has class number greater than 1 (namely 3).[2]
- A cousin prime with 83.
- An emirp in base 10, because the reverse of 79, 97, is also a prime.[3]
- A Fortunate prime.[4]
- A circular prime.[5]
- A prime number that is also a Gaussian prime (since it is of the form Шаблон:Nowrap).
- A happy prime.[6]
- A Higgs prime.[7]
- A lucky prime.[8]
- A permutable prime, with ninety-seven.
- A Pillai prime,[9] because 23! + 1 is divisible by 79, but 79 is not one more than a multiple of 23.
- A regular prime.[10]
- A right-truncatable prime, because when the last digit (9) is removed, the remaining number (7) is still prime.
- A sexy prime (with 73).
- The n value of the Wagstaff prime 201487636602438195784363.
- Similarly to how the decimal expansion of 1/89 gives Fibonacci numbers, 1/79 gives Pell numbers, that is, <math>\frac{1}{79}=\sum_{n=1}^\infty{P(n)\times 10^{-(n+1)}}=0.0126582278\dots\ .</math>
- A Leyland number of the second kind.
In science
- The atomic number of the chemical element gold (Au) is 79.
In astronomy
- Messier object 79 (M79), a magnitude 8.5 globular cluster in the constellation Lepus
- New General Catalogue object 79 (NGC 79), a galaxy in the constellation Andromeda
In other fields
- Live Seventy Nine, an album by Hawkwind
- The years 79 BC, AD 79 or 1979
- The number of the French department Deux-Sèvres
- The ASCII code of the capital letter O
References
- ↑ Шаблон:Cite OEIS
- ↑ H. Cohen, A Course in Computational Algebraic Number Theory, GTM 138, Springer Verlag (1993), Appendix B2, p.507. The table lists fields by discriminant, which is 4p for Q[[[:Шаблон:Sqrt]]] when p is congruent to 3 modulo 4, as is the case for 79, so the entry appears at discriminant 316.
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite web
- ↑ Numbers such that every cyclic permutation is a prime.
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite web
