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Search: id:A124050
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| A124050 |
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Difference between first Chen prime>10^n and 10^n. |
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+0
1
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| 1, 1, 1, 9, 7, 19, 37, 19, 7, 7, 19, 19, 61, 687, 97, 91, 79, 13, 79, 97, 151, 217, 427, 253, 667, 13, 127, 427, 457, 577, 1069, 349, 1147, 1267, 2527, 2833, 709, 871, 259, 361, 1651, 391, 2689, 649, 31, 3007, 1657, 2257, 3757, 5977, 1441, 2779, 5749, 367, 31
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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A033873(n)=<a(n)<=A124001(n) and a(n)=A033873(n) for n = 0,1,2,3,4,7,8,9,10, 25,44,54.
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EXAMPLE
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a(0)=1 because 2 is prime, 2+2=4 semiprime and 2-10^0=1,
a(1)=1 because 11 and 13 are twin primes and 11-10^1=1,
a(2)=1 because 101 and 103 are twin primes and 101-10^2=1,
a(3)=9 because 1009 is prime, 1011= 3*337 semiprime and 1009-10^3=9,
a(4)=7 because 10007 and 10009 are twin primes and 10007-10^4=7,
a(5)=19 because 100019 is prime, 100021= 29*3449 semiprime and 100019-10^5=19, etc.
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CROSSREFS
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Cf. A033873, A109611, A124001.
Sequence in context: A010547 A011405 A131724 this_sequence A107663 A038297 A144622
Adjacent sequences: A124047 A124048 A124049 this_sequence A124051 A124052 A124053
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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 03 2006
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