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).

2, 3, 6, 10, 18, 20, 25, 33, 40, 53, 56, 69, 79, 89, 95, 108

Offset: 1

Author

Matthew Vandermast, Mar 02 2003

Keywords

• nonn

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.

Crossrefs

Cf. A080997, A080998.

Formula

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