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Search: id:A124450
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| A124450 |
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Lesser of a pair of not necessarily distinct closest n-digit primes that add up to 10^n. |
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+0
5
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| 5, 47, 491, 4919, 49877, 499943, 4999913, 49999757, 499999931, 4999999937, 49999999811, 499999999769, 4999999998431, 49999999999619, 499999999999769, 4999999999998557, 49999999999998887, 499999999999999679
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Hans Havermann, Table of n, a(n) for n = 1..50
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FORMULA
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10^n - a(n) is prime.
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EXAMPLE
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10^1=5+5; 10^2=47+53; 10^3=491+509;
10^4=4919+5081; 10^5=49877=50123; 10^6=499943+500057;
10^7=4999913+5000087; 10^8=49999757+50000243;
10^9=499999931+500000069;
10^10=4999999937+5000000063}, etc.
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MATHEMATICA
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Table[ h =10^n/2; c=0; While[ PrimeQ[ h-c ]==False || PrimeQ[ h+c ]==False, c++ ]; h-c, {n, 1, 50} ] (from Hans Havermann, Nov 02 2006)
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CROSSREFS
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Cf. A065577 = number of Goldbach partitions of 10^n.
Cf. A124013.
Sequence in context: A122501 A049281 A124267 this_sequence A136023 A074192 A058806
Adjacent sequences: A124447 A124448 A124449 this_sequence A124451 A124452 A124453
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Nov 02 2006
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EXTENSIONS
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Edited by njas May 15 2008 at the suggestion of R. J. Mathar.
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