A336299 (Least prime > prime(n)/2) - (greatest prime < prime(n)/2).

1, 2, 2, 2, 4, 4, 2, 4, 4, 2, 4, 4, 6, 6, 2, 2, 6, 6, 6, 4, 2, 4, 6, 6, 6, 6, 6, 6, 6, 6, 4, 4, 6, 6, 6, 4, 6, 6, 8, 8, 8, 8, 4, 4, 4, 4, 14, 14, 14, 14, 14, 14, 4, 6, 6, 6, 2, 10, 10, 10, 6, 6, 6, 6, 4, 6, 6, 6, 6, 2, 10, 10, 10, 2, 4, 2, 12, 12, 12, 12, 12

Offset: 3

Author

Clark Kimberling, Nov 16 2020

Keywords

• nonn

Examples

			Prime(3)/2 = 2.5, so that a(3) = 3 - 2 = 1.
Prime(4)/2 = 3.5, so that a(4) = 5 - 3 = 2.
		

Crossrefs

Cf. A000040, A039734, A336298.

Programs

Mathematica

z = 120; t = Table[NextPrime[Prime[n]/2], {n, 3, z}]; (* cf. A039734, A079953 *)
u = NextPrime[t, -1]  (* A336298 *)
t - u  (* A336299 *)

PARI

a(n) = my(x=prime(n)/2); nextprime(x) - precprime(x); \\ Michel Marcus, Nov 18 2020