### About the Number 47 (forty-seven)

On 25 July 2008, computer science professor Randy Pausch died from pancreatic cancer, but I didn't get to blog about it until yesterday (August 3rd). Dr. Pausch was 47 years young at the time of his death.

Today, 4 August 2008, U.S. presidential candidate Barack Obama turned 47 years of old.

Here is stuff about the number 47.

```   47 is a natural, whole, integer
47 is odd
47 is unhappy
47 is not a Harshad number
47 is prime
...Cousin prime with 43
...Safe prime with 23
...Sexy prime with 53
...Sexy prime with 41
...OEIS:002145 (4n+3; n=11)
...Left-truncatable
...prime triplet {41, 43, 47}
47 is undulating
47 in octal is 057
47 in hexadecimal is 0x2f
47 in binary is 101111 (is odious)
47 nearest square numbers: -11...2 (36 ...49 )
sqrt(47) = 6.85565
ln(47) = 3.85015
log(47) = 1.6721
47 reciprocal is 0.02127659574468085106382978723404
47 is 14.9606 Pi years
47 is 2 score and 7 years
```

MathBabbler first... 47 is a Carol number.

```    a(n) = (2^n - 1)^2 - 2

a(1) = (2^1 - 1)^2 - 2 = (2 - 1)^2 - 2 = 1^2 - 2 = 1 - 2 = -1
a(2) = (2^2 - 1)^2 - 2 = (4 - 1)^2 - 2 = 3^2 - 2 = 9 - 2 = 7
a(3) = (2^3 - 1)^2 - 2 = (8 - 1)^2 - 2 = 7^2 - 2 = 49 - 2 = 47
```

About 47 from the Cloudy Cloud Calculator...

```   47 + 2 = 49   and    47 * 2 = 94
```

MathBabbler was born in 1947 + 10.

RoadHacker has driven on MO Hwy-47 and NM Hwy-47.

Hmmm... do all numbers equal 47? tech.groups.yahoo.com

##### Update::2012.09.19

BAB::The Percent 47% Has Gone Viral [19 September 2012]

##### Update::2013.01.21

GDT had fun with the number 47 on 21 January 2013.

```   MathBabbler Number Analyst (MBNA) output:
=========================================
47 is a natural, whole, integer
47 is odd
47 proper divisors are: 1,
47 is deficient (sum of divisors is 1)
47 is unhappy
47 is a Squarefree Number
47 is not a Harshad number
47 is prime
...Cousin prime with 43
...Safe prime with 23
...Sexy prime with 53
...Sexy Triplet prime with 53, 59
...Sexy prime with 41
...Truman Gerald prime with 17
...OEIS:002145 (4n+3; n=11)
...Left-truncatable
...Eisenstein
...prime triplet {41, 43, 47}
47 is undulating
47 is a Lucas number(29+18)
47 is a Thabit number
47 is ThurmNumber
47 in octal is 057
47 in hexadecimal is 0x2f
47 in binary is 101111 (is odious)
47 nearest square numbers: -11...2 (36...49 )
sqrt(47) = 6.85565
ln(47) = 3.85015
log(47) = 1.6721
47 reciprocal is .02127659574468085106382978723404
47! is 2.58623e+59
47 is 14.9606 Pi years
47 is 2 score and 7 years
47 written as a Roman numeral is XLVII
47 = 24^2 - 23^2 and 24 + 23 = 47
```

4712 is 55 and MathBabbler was 55 years young when he record this update.

Creator: Gerald Thurman [gthurman@gmail.com]
Created: 04 August 2008 