A033597 (nextprime(n)+prevprime(n))/2.

4, 5, 6, 8, 9, 9, 9, 10, 12, 14, 15, 15, 15, 16, 18, 20, 21, 21, 21, 24, 26, 26, 26, 26, 26, 27, 30, 33, 34, 34, 34, 34, 34, 36, 39, 39, 39, 40, 42, 44, 45, 45, 45, 48, 50, 50, 50, 50, 50, 53, 56, 56, 56, 56, 56, 57, 60

Offset: 4

Author

N. J. A. Sloane

Keywords

• nonn

Programs

Mathematica

Table[(NextPrime[n]+NextPrime[n,-1])/2,{n,4,60}] (* Harvey P. Dale, Aug 29 2022 *)

Formula

2*a(n) = A151800(n) + A151799(n). - R. J. Mathar, Feb 06 2017