login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A079629 Number of twin prime pairs between p^2 and q^2 where (p,q) is the n-th twin prime pair. 4
2, 2, 2, 2, 2, 3, 5, 3, 7, 6, 6, 10, 13, 7, 8, 9, 9, 7, 12, 18, 14, 24, 19, 10, 21, 21, 20, 20, 19, 22, 19, 24, 24, 27, 25, 30, 27, 23, 34, 29, 21, 35, 38, 30, 32, 30, 33, 36, 33, 30 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Conjecturally a(n) is always positive. It seems that a(n) might tend to infinity.

a(n) = A071538(A006512(n)^2) - A071538(A001359(n)^2). - Reinhard Zumkeller, Feb 16 2008

LINKS

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

EXAMPLE

a(3)=2 because the third twin prime pair is (11,13) and there are 2 twin prime pairs between 121 and 169, namely (137,139) and (149,151).

MATHEMATICA

ntpp[{a_, b_}]:=Count[Differences[Select[Range[a^2+1, b^2], PrimeQ]], 2]; ntpp/@ Select[Partition[Prime[Range[300]], 2, 1], #[[2]]-#[[1]]==2&] (* Harvey P. Dale, Oct 04 2019 *)

CROSSREFS

Cf. A057767.

Cf. A137859, A137860.

Sequence in context: A029105 A079954 A114968 * A029116 A064770 A322073

Adjacent sequences: A079626 A079627 A079628 * A079630 A079631 A079632

KEYWORD

easy,nonn

AUTHOR

Paul Boddington, Jan 30 2003

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 3 03:47 EST 2022. Contains 358511 sequences. (Running on oeis4.)