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Search: id:A161811
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| A161811 |
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Difference between nonprime(n+2) and nonprime(n). |
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+0
1
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| 4, 5, 4, 3, 2, 3, 4, 3, 2, 3, 4, 3, 2, 3, 3, 2, 2, 2, 3, 4, 3, 2, 2, 2, 3, 3, 2, 3, 4, 3, 2, 3, 3, 2, 2, 2, 3, 3, 2, 2, 2, 3, 4, 3, 2, 2, 2, 3, 3, 2, 3, 4, 3, 2, 2, 2, 3, 3, 2, 3, 3, 2, 2, 2, 3, 3, 2, 2, 2, 2, 2, 3, 3, 2, 3, 4, 3, 2, 3, 4, 3, 2, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 2, 3, 3, 2, 2, 2, 3, 4
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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"nonprime(n)" is used for "n-th nonprime". Here the nonprimes start at 0 (see A141468), so nonprime(1) to nonprime(15) are 0, 1, 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22.
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FORMULA
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a(n) = A141468(n+2)-A141468(n).
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EXAMPLE
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nonprime(1+2)-nonprime(1) = 4-0; so a(1) = 4.
nonprime(5+2)-nonprime(5) = 10-8; so a(5) = 2.
nonprime(11+2)-nonprime(11) = 20-16; so a(11) = 4.
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CROSSREFS
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Cf. A031131, A141468.
Sequence in context: A120867 A011427 A071413 this_sequence A016717 A031349 A036444
Adjacent sequences: A161808 A161809 A161810 this_sequence A161812 A161813 A161814
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KEYWORD
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nonn
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AUTHOR
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Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Jun 20 2009
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EXTENSIONS
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Edited, corrected (a(11)=2 replaced by 4) and extended by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Jun 24 2009
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