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Search: id:A081028
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| A081028 |
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Numbers n such that n-th term of A080997 is prime; a(n) is ranking of n-th prime number among the positive integers in terms of centrality (cf. A080997 for explanation of this concept). |
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4
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| 2, 3, 6, 10, 18, 20, 25, 33, 40, 53, 56, 69, 79, 89, 95, 108
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Let p(n) be the n-th prime. In order for the centrality rankings of all numbers from 1 to p(n) to be known, it is necessary for the numbers that occupy all of the ranking positions from 1 to a(n) to be determined.
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FORMULA
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Formula for centrality of n: A018804(n)/n^2 (see also A080997).
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CROSSREFS
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Cf. A080997, A080998.
Sequence in context: A123908 A026397 A026779 this_sequence A065441 A075531 A066067
Adjacent sequences: A081025 A081026 A081027 this_sequence A081029 A081030 A081031
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KEYWORD
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nonn
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AUTHOR
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Matthew Vandermast (ghodges14(AT)comcast.net), Mar 02 2003
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