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%I #5 Mar 30 2012 17:27:18
%S 2,3,6,10,18,20,25,33,40,53,56,69,79,89,95,108
%N 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).
%C 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.
%F Formula for centrality of n: A018804(n)/n^2 (see also A080997).
%Y Cf. A080997, A080998.
%K nonn
%O 1,1
%A _Matthew Vandermast_, Mar 02 2003