A137859 Number of primes between the n-th squared twin prime pair.

5, 6, 9, 11, 16, 20, 32, 30, 42, 42, 49, 58, 76, 77, 75, 82, 90, 91, 99, 107, 125, 151, 151, 145, 165, 189, 168, 189, 194, 211, 241, 244, 246, 259, 262, 290, 304, 300, 311, 314, 318, 341, 372, 360, 366, 356, 381, 404, 391, 389, 431, 433, 450, 462, 477, 494, 493

Offset

1,1

Comments

a(n) = Sum_{k=A001359(n)^2..A006512(n)^2} A010051(k).

a(n) = A000720(A006512(n)^2) - A000720(A001359(n)^2).

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

a(4) = #{293,307,311,313,317,331,337,347,349,353,359} = 11.

Mathematica

PrimePi[#[[2]]^2]-PrimePi[#[[1]]^2]&/@Select[Partition[ Prime[ Range[ 200]], 2, 1], #[[2]]-#[[1]]==2&] (* Harvey P. Dale, Nov 10 2017 *)

Crossrefs

Cf. A079629, A137860.

Cf. A000720, A001359, A006512, A010051.

Sequence in context: A334815 A220968 A179662 * A082576 A177731 A074185

Adjacent sequences: A137856 A137857 A137858 * A137860 A137861 A137862

Keyword

nonn

Author

Reinhard Zumkeller, Feb 16 2008

Status

approved