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 2008-11-01, 19:30 #1 davar55     May 2004 New York City 5·7·112 Posts Strings of Digits Where is the longest string of consecutive 0's in a known prime? What about 1's, 2's, 3's, etc.? What if we restrict to the known Mersenne primes?
2008-11-01, 19:38   #2
retina
Undefined

"The unspeakable one"
Jun 2006
My evil lair

11001011001002 Posts

Quote:
 Originally Posted by davar55 Where is the longest string of consecutive 0's in a known prime?
[pedantic]
Can we assume you are not referring to leading zeros? Can we assume you are not referring to trailing zeros after the radix point? Can we assume base 10?
[/pedantic]

2008-11-01, 19:52   #3
R. Gerbicz

"Robert Gerbicz"
Oct 2005
Hungary

62516 Posts

Quote:
 Originally Posted by davar55 Where is the longest string of consecutive 0's in a known prime? What about 1's, 2's, 3's, etc.? What if we restrict to the known Mersenne primes?
Using :http://primes.utm.edu/primes/search.php
and searching for 10^ we can get probably the best known solutions for digit=0 and 9: p=98035*10^196070+1 containing 196069 consecutive 0's.
q=99*10^139670-1 containing 139670 consecutive 9's. Since both of them are on the top5000 list, it is possible to check remaining primes on the list, if there is a better solution or not.

2008-11-01, 20:38   #4
davar55

May 2004
New York City

5·7·112 Posts

Quote:
 Originally Posted by retina [pedantic] Can we assume you are not referring to leading zeros? Can we assume you are not referring to trailing zeros after the radix point? Can we assume base 10? [/pedantic]
Hmm ... no lead zeros and only integral parts. But if we allow other bases,
all bets but 1111111........1111111 are off !

 2008-11-01, 23:32 #5 Jens K Andersen     Feb 2006 Denmark 2·5·23 Posts n is the largest number of consecutive digits d in the 46 known Mersenne primes 2^p-1 with index m=1..46. d n m p 0 9 46 43112609 1 9 43 30402457 2 8 40 20996011 3 8 40 20996011 4 7 43 30402457 4 7 45 37156667 4 7 46 43112609 5 7 39 13466917 5 7 41 24036583 5 7 43 30402457 5 7 44 32582657 5 7 45 37156667 5 7 46 43112609 (3 times) 6 7 42 25964951 6 7 44 32582657 6 7 46 43112609 7 7 43 30402457 7 7 45 37156667 (2 times) 7 7 46 43112609 8 8 43 30402457 9 8 39 13466917
 2008-11-02, 00:08 #6 Jens K Andersen     Feb 2006 Denmark 23010 Posts Fot other digits than 0 and 9, the best I could spot in the complete Prime Pages database is (8*10^11083-8*10^1003+9)/9 which starts with 10080 8's. That would be easy to beat with a new prime.

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