Nói nhỏ :

Mỗi người sinh ra trên cõi đời này có một cơ địa , một tinh cách riêng . Sự đấu tranh sinh tồn và các yếu tố may mắn hình thành nên số phận . Nhưng cuộc đời dù lê thê cỡ nào cũng chỉ là hữu hạn và ngắn ngủi so với thế giới tự nhiên.Ta bước vào nghiệp dạy Toán như một lẽ thường vì ta đam mê sự suy luận sáng tạo , tính kiên trì ; sự chính xác và được tự do cô đơn.

Thứ Bảy, 15 tháng 4, 2017

Tìm hiểu về số Mersenne

What is a Mersenne Prime Number?

A Mersenne Number is a number that is equal to one less than a power of 2, or (2^n-1) where n is any positive integer. Mersenne numbers are named after Marin Mersenne, a French monk.
A Mersenne Prime Number is a prime number that happens to also be a Mersenne Number. A Mersenne Prime Number will always have a value equal to (2^n-1) where n is one of a selected list of positive prime numbers.
When I discovered that there was a formula for "Mersenne" prime numbers, I wrote another program for that, which gave me these results and is listed later on this page:
2^2-1 = 3
2^3-1 = 7
2^5-1 = 31
2^7-1 = 127
2^13-1 = 8191
2^17-1 = 131,071
2^19-1 = 524,287
2^31-1 = 2,147,483,647
As mentioned above, every known "perfect number" can be generated from a "Mersenne prime". If (2^n-1) describes a "Mersenne prime," then the matching "perfect number" is equal to:
2 ^ (n-1) * ( 2^n - 1)
where n = 2, 3, 5, 7, 13, 17, 19, 31 or other "mersenne" exponents. All of the known "Mersenne" exponents are listed in one of the sections above.
Can we prove that every "Mersenne Prime Number" can generate a corresponding Perfect number? Yes, we can.
Can we prove that every possible "perfect" number can be generated from a "Mersenne" prime? No, we cannot. (I'm hoping that someday someone will find an ODD "perfect" number, and an odd "perfect" number can NOT come from a "Mersenne" prime.)

List of Known Mersenne Prime Numbers

#
2p-1
Digits
Date Discovered
Discovered By
Method / Hardware
Perfect Number
1
22-1
1
c. 500 BCE
Ancient Greek mathematicians
2
23-1
1
c. 500 BCE
Ancient Greek mathematicians
3
25-1
2
c. 275 BCE
Ancient Greek mathematicians
4
27-1
3
c. 275 BCE
Ancient Greek mathematicians
5
213-1
4
1456
Anonymous
trial division
6
217-1
6
1588
Pietro Cataldi
trial division
7
219-1
6
1588
Pietro Cataldi
trial division
8
231-1
1772
Leonhard Euler
Enhanced trial division
9
261-1
1883
Ivan Mikheevich Pervushin
Lucas sequences
10
289-1
1911 Jun
R. E. Powers
Lucas sequences
11
2107-1
1914 Jun 11
R. E. Powers
Lucas sequences
12
2127-1
1876 Jan 10
Édouard Lucas
Lucas sequences
13
2521-1
1952 Jan 30
Raphael M. Robinson
L-L / SWAC
14
2607-1
1952 Jan 30
Raphael M. Robinson
L-L / SWAC
15
21,279-1
1952 Jun 25
Raphael M. Robinson
L-L / SWAC
16
22,203-1
1952 Oct 07
Raphael M. Robinson
L-L / SWAC
17
22,281-1
1952 Oct 09
Raphael M. Robinson
L-L / SWAC
18
23,217-1
1957 Sep 08
Hans Riesel
L-L / BESK
19
24,253-1
1961 Nov 03
Alexander Hurwitz
L-L / IBM 7090
20
24,423-1
1961 Nov 03
Alexander Hurwitz
L-L / IBM 7090
21
29,689-1
1963 May 11
Donald B. Gillies
L-L / ILLIAC II
22
29,941-1
1963 May 16
Donald B. Gillies
L-L / ILLIAC II
23
211,213-1
1963 Jun 02
Donald B. Gillies
L-L / ILLIAC II
24
219,937-1
1971 Mar 04
Bryant Tuckerman
L-L / IBM 360/91
25
221,701-1
1978 Oct 30
Landon Curt Noll & Laura Nickel
L-L / CDC Cyber 174
26
223,209-1
1979 Feb 09
Landon Curt Noll
L-L / CDC Cyber 174
27
244,497-1
1979 Apr 08
Harry Lewis Nelson & David Slowinski
L-L / Cray 1
28
286,243-1
1982 Sep 25
David Slowinski
L-L / Cray 1
29
1988 Jan 28
Walter Colquitt & Luke Welsh
L-L / NEC SX-2
30
1983 Sep 19
David Slowinski
L-L / Cray X-MP
31
1985 Sep 01
David Slowinski
L-L / Cray X-MP/24
32
1992 Feb 19
David Slowinski & Paul Gage
L-L / Maple on Harwell Lab Cray-2
33
1994 Jan 04
David Slowinski & Paul Gage
L-L / Cray C90
34
1996 Sep 03
David Slowinski & Paul Gage
L-L / Cray T94
35
GIMPS / Joel Armengaud
L-L / Prime95 on 90 MHz Pentium PC
36
GIMPS / Gordon Spence
L-L / Prime95 on 100 MHz Pentium PC
37
GIMPS / Roland Clarkson
L-L / Prime95 on 200 MHz Pentium PC
38
GIMPS / Nayan Hajratwala
L-L / Prime95 on 350 MHz Pentium II IBM Aptiva
39
GIMPS / Michael Cameron
L-L / Prime95 on 800 MHz Athlon Thunderbird
40
GIMPS / Michael Shafer
L-L / Prime95 on 2 GHz Dell Dimension
41
GIMPS / Josh Findley
L-L / Prime95 on 2.4 GHz Pentium 4 PC
42
GIMPS / Martin Nowak
L-L / Prime95 on 2.4 GHz Pentium 4 PC
43
GIMPS / Curtis Cooper & Steven Boone
L-L / Prime95 on 2 GHz Pentium 4 PC
44
GIMPS / Curtis Cooper & Steven Boone
L-L / Prime95 on 3 GHz Pentium 4 PC
45
GIMPS / Hans-Michael Elvenich
L-L / Prime95 on 2.83 GHz Core 2 Duo PC
46*
GIMPS / Odd M. Strindmo
L-L / Prime95 on 3 GHz Core 2 PC
47*
GIMPS / Edson Smith
L-L / Prime95 on Dell Optiplex 745
48*
GIMPS / Curtis Cooper
L-L / Prime95 on Intel Core2 Duo E8400 @ 3.00GHz
49*
GIMPS / Curtis Cooper
L-L / Prime95 on Intel i7-4790 @ 3.60GHz