A166236 Absolute value of (n-th odd prime minus n-th odd nonprime)/2.

1, 2, 4, 5, 6, 5, 7, 6, 5, 7, 6, 5, 6, 5, 5, 3, 4, 4, 3, 4, 3, 2, 1, 2, 3, 2, 1, 1, 1, 5, 6, 8, 8, 12, 11, 12, 14, 13, 15, 17, 17, 19, 19, 19, 19, 23, 27, 28, 27, 28, 28, 28, 32, 34, 34, 34, 34, 36, 37, 37, 40, 46, 47, 47, 48, 53, 53, 56, 56, 55, 57, 60, 62, 63, 64, 65, 68, 68, 71, 73

Offset: 1

Author

Juri-Stepan Gerasimov, Oct 09 2009

Keywords

• nonn

Examples

			a(1)=abs(3-1)/2=1; a(2)=abs(5-9)/2=abs(-2)=2; a(3)=abs(7-15)/2=abs(-4)=4.
		

Links

• G. C. Greubel, Table of n, a(n) for n = 1..5000

Crossrefs

Cf. A014076, A065091.

Programs

Mathematica

A014076 := Select[Range@500, ! PrimeQ@# && OddQ@# &]; A065091 := Prime[Range[2, 500]]; Table[Abs[A065091[[n]] - A014076[[n]]]/2, {n, 1, 50}] (* G. C. Greubel, Sep 17 2017 *)

Formula

a(n) = abs(A065091(n) - A014076(n))/2.

Extensions

Entries checked by R. J. Mathar, May 21 2010