A275219 Number of primes between prime (n)*prime (n + 1) and prime (n + 1) prime (n + 2).

3, 5, 10, 13, 13, 19, 18, 37, 33, 35, 51, 34, 32, 61, 78, 58, 59, 78, 50, 67, 90, 91, 137, 133, 66, 62, 64, 71, 212, 241, 133, 106, 168, 184, 122, 181, 162, 165, 192, 139, 216, 216, 110, 109, 264, 463, 337, 127, 123, 210, 184, 263, 355, 282, 271, 200, 193

Offset

1,1

Links

Clark Kimberling, Table of n, a(n) for n = 1..1000

Example

The primes between 15 and 35 are 17,19,23,29,31, so that a(2) = 5.

Mathematica

z = 200; t = Table[Prime[n] Prime[n + 1], {n, 1, 2*z}]  (* A006094 *)
Table[PrimePi[t[[n + 1]]] - PrimePi[t[[n]]], {n, 1, z}] (* A275219 *)

Prog

(PARI) a(n) = primepi(prime(n+1)*prime(n+2)) - primepi(prime(n)*prime(n+1)) \\ Felix Fröhlich, Jul 22 2016

Crossrefs

Cf. A000040, A006094.

Sequence in context: A007557 A034746 A345176 * A080931 A299533 A309270

Adjacent sequences: A275216 A275217 A275218 * A275220 A275221 A275222

Keyword

nonn,easy

Author

Clark Kimberling, Jul 20 2016

Status

approved