A063932 Average of largest prime less than or equal to n and smallest prime greater than or equal to n.

2, 3, 4, 5, 6, 7, 9, 9, 9, 11, 12, 13, 15, 15, 15, 17, 18, 19, 21, 21, 21, 23, 26, 26, 26, 26, 26, 29, 30, 31, 34, 34, 34, 34, 34, 37, 39, 39, 39, 41, 42, 43, 45, 45, 45, 47, 50, 50, 50, 50, 50, 53, 56, 56, 56, 56, 56, 59, 60, 61, 64, 64, 64, 64, 64, 67, 69, 69, 69, 71, 72, 73

Offset: 2

Author

Henry Bottomley, Aug 21 2001

Keywords

• nonn

Examples

			a(7) = (7 + 7)/2 = 7;
a(8) = (7 + 11)/2 = 9.
		

Links

• Harry J. Smith, Table of n, a(n) for n = 2..1000

Crossrefs

Interleaving of A000040 and A001223-1 copies of A024675. Cf. A063934.

Programs

Mathematica

Table[Mean[{NextPrime[n-1],NextPrime[n+1,-1]}],{n,2,80}] (* Harvey P. Dale, Nov 22 2011 *)

PARI

{ for (n=2, 1000, write("b063932.txt", n, " ", (precprime(n) + nextprime(n))/2) ) } \\ Harry J. Smith, Sep 02 2009

Formula

a(n) = (A007917(n) + A007918(n))/2 = n - A063933(n).