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A081028 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). 3
2, 3, 6, 10, 18, 20, 25, 33, 40, 53, 56, 69, 79, 89, 95, 108 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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.

LINKS

Table of n, a(n) for n=1..16.

FORMULA

Formula for centrality of n: A018804(n)/n^2 (see also A080997).

CROSSREFS

Cf. A080997, A080998.

Sequence in context: A026397 A193200 A026779 * A325232 A208479 A065441

Adjacent sequences:  A081025 A081026 A081027 * A081029 A081030 A081031

KEYWORD

nonn

AUTHOR

Matthew Vandermast, Mar 02 2003

STATUS

approved

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Last modified November 28 12:34 EST 2021. Contains 349402 sequences. (Running on oeis4.)